Abstract: The transition to clean and sustainable transportation highlights the importance of hydrogen and fuel cell technologies as promising solutions for reducing greenhouse gas emissions. This paper presents the development and assessment of an adaptive frequency separation-based energy management strategy using fuzzy logic for fuel cell–battery hybrid vehicles. The studied system integrates a proton exchange membrane fuel cell as the primary source and a lithium-ion battery as the secondary source, both interfaced with the DC bus through DC/DC converters. A PI controller ensures DC bus voltage stability, while a sliding mode hysteresis controller provides robust regulation of the fuel cell current. Unlike conventional frequency separation methods, which only allocate low-frequency demand to the fuel cell and high-frequency demand to the battery, the proposed strategy introduces an adaptive correction mechanism based on the state of charge (SOC) of the battery and instantaneous load variations. This ensures efficient power allocation according to source dynamics while actively regulating the SOC within a safe operating range. Simulation results under UDDS and NEDC driving cycles confirm that the proposed strategy maintains the SOC between 40% and 80% with convergence toward the target value of 60%, while reducing the apparent hydrogen consumption by 30%. These improvements highlight the robustness and efficiency of the proposed strategy, making it a promising solution to extend the lifespan of hybrid energy sources in hybrid fuel cell electric vehicles.

Keywords: Energy management strategy | Frequency separation | Fuel cell hybrid electric vehicle | Fuzzy logic | Hydrogen | PI controller | Sliding-mode control

Abstract: Mandibular and maxillary bone regeneration is a significant challenge in orthodontics and maxillofacial surgery, particularly in patients with bone atrophy or advanced periodontal diseases. This study presents an innovative approach that integrates advanced imaging and manufacturing technologies to design and fabricate customized scaffolds based on data obtained through Cone Beam Computed Tomography (CBCT). The objective is to create biomimetic bone scaffolds suitable for infusion with autologous stem cells, promoting functional bone regeneration. The workflow comprises three key stages. CBCT images are processed to reconstruct detailed three-dimensional models of the mandibular or maxillary structure. Then, using generative optimization algorithms and surface subroutines in commercial CAD software, scaffolds are designed to replicate the mechanical, geometric, and biological properties of natural bone. The scaffolds are fabricated using 3D printing techniques with biocompatible and biodegradable materials. 3D printing enables high precision in creating porous structures optimized for vascularization, cellular integration, and mechanical support. This multidisciplinary approach, combining medical imaging, CAD/CAM design, and additive manufacturing, offers an advanced solution to address the challenges of bone regeneration in orthodontics. Preliminary results suggest that infusing scaffolds with stem cells could significantly accelerate bone regeneration and improve integration with surrounding tissues. Future studies will focus on preclinical validation of scaffolds.

Keywords: Biocompatible material | Biodegradable material | Bone scaffold | DICOM images | Mandibular and Maxillary Reconstruction

Abstract: Lost-wax casting is an ancient technique of great precision, used for the creation of bronze artefacts. The artist makes the model in clay or plasticine and then creates the plaster or silicone mold. Inside the mould, wax is brushed to the ideal thickness of 5 to 6 mm and then wax “straws” were added at appropriate positions to allow optimal filling of the mould during bronze casting, starting with the lowest volumes. Finally, the wax model is incorporated into a refractory mass that surrounds it internally and externally and forms the cavity into which the bronze is poured. In this research, the results were obtained by analysing an innovative digital technique that avoids the creation of the mould and shrinkage during the intermediate stages of bronze production. In fact, using a 3D scanner and the latest rapid prototyping techniques, an accurate reproduction of the original clay model was recreated. The moulded model replaces the wax model. It is also enclosed between two forms of refractory material and, due to its similar melting temperature and flow properties, minimises build time and improves accuracy. The studied methodology also allows a more precise assignment and greater control of all surface thicknesses through a discretised digital finite element (FE) model analysis.

Keywords: Bronze sculptures’ reconstruction | Laser scanning technology | Lost-wax bronze casting | Mold withdrawal | Rapid prototyping

Abstract: Accurate three-dimensional (3D) reconstruction of individual dental elements from cone-beam computed tomography (CBCT) data is critical for adaptive prosthetic design and occlusal simulation in digital dentistry. However, challenges persist due to the complex morphology of teeth, the similar radiodensities of hard tissues, and the limited resolution of CBCT in capturing interproximal surfaces between adjacent teeth. This study presents a semi-automated, open-source compatible workflow that integrates CBCT image segmentation with the reconstruction of missing interproximal molar regions using Non-Uniform Rational B-Spline (NURBS) surface modeling. Molar datasets from CBCT acquisitions were segmented into 3D Slicer open-source software and refined to isolate individual teeth. Missing surface regions were reconstructed using third-degree NURBS patches in Rhinoceros® ver. 8 commercial software. Method reconstruction accuracy was quantitatively evaluated on 14 M by applying the method to manually created voids on intact tooth models. The average root-mean-square error (RMSE) and Hausdorff distance were 0.041 ± 0.015 mm and 0.049 ± 0.023 mm, respectively. The resulting models exhibited high surface continuity and anatomical fidelity, making them suitable for Computer Aided Engineering (CAE) analysis and prosthetic customization. This approach enables reproducible, high-precision dental modeling and represents a promising step toward fully automated 3D reconstruction workflows in clinical practice.

Keywords: CBCT segmentation | Digital prosthodontics | Molar morphology subdivision | NURBS modeling

Abstract: The present study introduces a novel approach for pattern recognition to analyze the surface hardness of metal parts made by 3D selective laser melting (SLM). A printed part’s hardness is further influenced by post-processing, printing parameters, and post-print material handling. Layer by layer, material is deposited in 3D printing, sometimes referred to as additive manufacturing, to turn a digital design into a tangible product. More complex and adaptable designs are possible because 3D printing adds material rather than removes it, in contrast to conventional manufacturing techniques (such as machining or molding). The current work models the surface hardness of 3D selective laser melting of metal materials using genetic programming and network theory. To assess the hardness of 3D selective laser melting of metal materials, we introduce a novel pattern recognition technique. We apply fractal geometry analysis to determine the complexity of 3D selective laser melting of metal materials.

Keywords: Additive manufacturing | Fractal geometry | Genetic programming | Network theory | Selective laser melting | Surface hardness

Abstract: The high-performance car industry demands increasingly lightweight and durable components, driving the development of innovative manufacturing techniques and increasingly high performing materials. Among critical automotive components, mechanical hinges with close supports play a key role in ensuring high functionality in limited spaces while contributing to the structural efficiency and safety of vehicles. This study examines an accurate design and manufacturing process for hinges with close-range bushings. In particular, the manufacturing technology of the Polytetrafluoroethylene (PTFE)-coated bronze bushing connected with a FeZnNi pin inside the hinges was analysed and optimised. A predictive mathematical model was developed and validated with measurements using an appropriate experimental set-up created by the authors. Specifically, the experimental tests were performed by simulating and automating the rotation of the hinge; this made it possible to accurately assess the resistant torques due to assembly errors, tightening torques, geometric and dimensional tolerances. Through the proposed methodology, the resistant torque was related to the correct manufacture, the PTFE coefficient of friction, and the operating temperatures, guaranteeing long-lasting performance and reliable integration of hinge components. The results demonstrated that the proposed methodology enhances the manufacturing process by allowing the production of reliable and high-performance mechanical hinges.

Keywords: Fe-Zn-Ni alloy | Geometric and dimensional tolerances | Long-lasting performance | PTFE-coated bronze bushing | Resistant torque

Abstract: Car seat comfort represents a fundamental dimension of automotive ergonomics, yet its assessment and optimization remain predominantly reliant on subjective feedback and iterative physical prototyping, limiting scalability and responsiveness in the design process. This study presents a novel data-driven framework that synergistically integrates statistical analysis and deep learning architectures enhanced with attention mechanisms to predict perceived driver discomfort from pressure distribution patterns. A comprehensive dataset acquired from 192 participants was used to extract biomechanical descriptors, such as contact area and peak pressure, across 9 anatomical regions, which were subsequently correlated with subjective discomfort ratings collected on a 10-point Likert scale. The proposed hybrid deep neural network achieved a modelling accuracy of R2 = 0.82 for overall discomfort, with peak pressure emerging as the most influential factor (Spearman’s r = 0.78). Moreover, Finite Element Analysis (FEA) was employed to validate geometry refinements suggested by the AI model, resulting in an 18% reduction in peak seat pressure without compromising structural integrity. The findings underscore the transformative potential of integrating artificial intelligence with CAD–CAE methodologies to enable rapid, user-centered, and simulation-driven ergonomic design early in the vehicle development cycle, minimizing the need for physical prototypes and enhancing occupant comfort.

Keywords: AI-Driven Comfort Models | Deep Learning with Attention Mechanisms | Ergonomic Seat Design Optimization | Finite Element Validation of Human-Centric Design | Pressure Mapping and Biomechanical Analysis

Abstract: Chewing simulators are essential tools in dentistry, as they enable the performance of innovative dental restorative materials to be analysed under realistic conditions. These devices replicate the complex movements and forces involved in mastication, enabling simulations of material wear and fatigue resistance. Their design and manufacture require a multidisciplinary approach that integrates mechanical engineering, materials science and dentistry, allowing the development of tools capable of improving the understanding of chewing processes and the effectiveness of dental treatments. This research focuses on a review of the main types of chewing articulators, highlighting the design and manufacturing aspects necessary to analyse the wear and the fatigue resistance of restorative materials. Construction characteristics, technologies employed and the most effective configurations for simulating realistic intra-oral conditions, including cyclic movements and variable forces, are highlighted. This study provides an overview of the main types of articulators currently in existence and their fabrication techniques, highlighting the importance of designing accurate, versatile, and increasingly reliable simulators. This allows to improve performance evaluation of dental materials while achieving greater success in patient-centred dental practices.

Keywords: Chewing articulators | Chewings’ manufacture technique | Patient-centred treatment | Restorative material testing | Simulator design

Abstract: Maintenance activities on transportation infrastructures, particularly on the underside of bridges and viaducts, present critical challenges related to safety, accessibility and cost-efficiency. Conventional solutions, such as scaffolding or mobile platforms, often exhibit substantial operational limitations. In this context, modular articulated robotic arms present a promising, safer, and more flexible alternative. This study introduces a functionality and data-driven design methodology for the modular development of articulated robotic arms specifically tailored for bridge maintenance applications. The proposed approach integrates Finite Element Analysis with clustering algorithms to identify mechanically equivalent joint modules based on their structural response under realistic loading conditions, including self-weight and external forces. Subsequently, topology optimisation techniques are applied to refine the geometry of selected joints, enhancing their stiffness-to-weight ratio while preserving manufacturability and modularity. Additionally, the application of Geometric Dimensioning and Tolerancing ensures mechanical reliability and precision during assembly. The effectiveness of the methodology is demonstrated through comparative Finite Element Analysis assessments between the initial and optimised designs, along with the construction of a functional prototype. The proposed framework paves the way for scalable, robust, and repeatable robotic solutions in the infrastructure maintenance sector.

Keywords: Bridge Maintenance | Clustering Algorithms | Geometric Dimensioning and Tolerancing | Modular Robotic Arms | Topology Optimisation

Abstract: This study investigates the development of advanced technologies for subsurface monitoring, with significant implications in geophysics, natural hazard mitigation, and environmental engineering. Specifically, the research focuses on the application of Distributed Acoustic Sensing using a 28 km long scientific electro-optical cable deployed in deep-sea conditions as a sensor for the detection of vibrations and mechanical disturbances along its path. DAS enables continuous, high-resolution monitoring of the underwater acoustic environment. However, the system’s sensitivity and accuracy are strongly influenced by the degree of mechanical coupling between the optical fiber and the surrounding medium, which in turn depends on both the structural characteristics of the cable and the nature of the seabed where it is installed. To address these challenges, a digital twin of the experimental configuration has been developed. This virtual model allows for the simulation and optimization of the cable’s mechanical behavior under various environmental conditions. Particular emphasis is placed on the analysis of the cable’s static equilibrium state, which is essential for understanding the actual transmission of mechanical stress to the optical fiber and for the calibration of numerical models against experimental data. The manuscript is organized as follows: Introduction, Cable Architecture, Experimental Setup, Methodology, Results, and Conclusions.

Keywords: Digital twin | Distributed Acoustic Sensing (DAS) | Mechanical Coupling | Optical Fibers

Abstract: The GeoINQUIRE project (GEO_INQUIRE, HORIZON-INFRA-2021-SERV-01, GA - 101058518) is a European initiative aimed at developing innovative research infrastructures for monitoring the subsurface, with applications in the fields of geophysics, natural hazards and environmental engineering. In this context, the Laboratori Nazionali del Sud – Istituto Nazionale di Fisica Nucleare are working on the application of Distributed Acoustic Sensing (DAS) technology, using a proprietary 28 km-long scientific deep-sea electro-optical cable as sensor to detect vibrations and mechanical changes along its path, to provide continuous, high-resolution monitoring of the soundscape. The effectiveness of DAS in such applications depends on the ability to accurately simulate the response of the system, since the mechanical coupling between optical fiber and soil, mediated by the cable jacket, varies significantly depending on the type of cable used and the characteristics of the soil (rocky, sandy, etc.). To address this issue, the development of a digital twin of the configuration has been initiated to model, simulate and optimize the behaviour of the optical fiber under different operating and environmental conditions and using cables different manufacture. The integration of experimental data into digital simulations enables the prediction and improvement of DAS performance, helping to optimize design solutions and promote the evolution of smart manufacturing.

Keywords: Digital twin of optical fiber cable | Distributed Acoustic Sensing | Mechanical coupling | Modal analysis | Optical fibers cable manufacture

Abstract: Additive manufacturing (AM) enables customized, efficient restorative workflows, though the accuracy of 3D-printed restorations may be compromised by polymerization, sintering shrinkage, and post-processing. This study evaluated the geometric accuracy of 3D-printed partial restorations compared with the computer-aided design (CAD) reference. The null hypothesis stated that no significant differences would be found between Varseo Smile Crownplus (by BEGO, Italy) and IRIXMax (by DWS System, Italy) materials, which are printed and cured with different technologies. A model was prepared for an overlay and designed with a 1.5 mm uniform thickness. Restorations were produced in two groups with two different printing processes: DLP (digital light processing)-printed Varseo Smile Crownplus and SLA (stereolithography)-printed IRIXMax. Six samples per group were printed at 90° orientation and scanned. Meshes were aligned to the master geometry via pre-alignment and ICP (Iterative Closest Point) registration. Deviations were quantified in CloudCompare using mean, standard deviation (SD), and 90th percentile values. IRIXMax showed the lowest deviations from the ideal geometry, while Varseo Smile Crownplus exhibited greater variability. Pairwise comparisons found IRIXMax significantly more accurate than Varseo Smile Crownplus. Color maps confirmed material-specific deviation patterns. IRIXMax provided the highest geometric accuracy. Material-specific calibration is essential for reliable 3D-printed definitive restorations.

Keywords: 3D printing | dental restorations | deviation analysis geometric accuracy | internal gap | marginal fit | resin-based composites | trueness

Abstract: Brain arteriovenous malformations (AVMs) are complex cerebrovascular lesions characterized by abnormal direct connections between arteries and veins, resulting in altered hemodynamics and an increased risk of rupture. Following PRISMA, a comprehensive review on CFD-based modelling in brain AVMs was conducted across major scientific databases, including Pub-Med/MEDLINE, Scopus, Web of Science, Google Scholar, EBSCO Academic Search and IEEE Xplore, evaluating its role in hemodynamic analysis and pre-procedural planning. Twenty-three studies met the inclusion criteria and were analyzed through both qualitative synthesis and bibliometric approaches. Bibliometric analysis revealed a growing research interest in image-based modelling, 4D flow imaging and virtual embolization after 2021. Despite recent advances in study of hemodynamics simulations, the application of computational fluid dynamics (CFD) to brain AVMs remains challenging due to their complex vascular architecture and highly heterogeneous flow patterns. Nevertheless, CFD remains an important imaging modality for characterizing the lesion and guiding pre-interventional decision making.

Keywords: 3D reconstruction | arteriovenous malformations (AVMs) | computational fluid dynamics (CFD) | neuroimage modelling | treatment planning

Abstract: The Geometric Product Specification (GPS) and Geometric Dimensioning and Tolerancing (GD&T) languages are the most powerful tools available for linking an ideal design to imperfectly manufactured parts that are never assembled with absolute accuracy. In the design of mechanical systems, the GPS and GD&T methods provide a symbolic language that allows for the complete, clear, and unambiguous definition of permissible variations from ideal geometries to ensure functionality and assemblability. This study proposes a methodology for assigning functional tolerances for the manufacture and assembly of hinges with pins supported by close-range bushings. A test machine was developed to measure the resistant torque in these types of hinges and an easy experimental procedure was used to measure and verify the cylindricity tolerance of the hinge bushings. This allowed a Design for Tolerancing (DfT) approach based on a correlation between the resistant torque values and dimensional and geometric errors. The proposed approach proved to be effective in establishing a relationship between shape, position and orientation errors and the functionality of the hinge.

Keywords: Design for Tolerancing (DfT) | Dimensional Management (DM) | Functional assembly design | Geometric Dimensioning and Tolerancing (GD&T) | Resistant torque

Abstract: In many areas of engineering, there is a growing need for accuracy and reliability of assembled systems. To ensure this accuracy, and to ensure the correct function of the part within the assembly, both dimensional and geometric tolerances must be correctly set at the design stage. An important tool, now irreplaceable in any CAD software, is the Geometric dimensioning and tolerancing (GD&T) control, which through algorithms can assign geometric and dimensional tolerances. In this manuscript authors present an original procedure for measuring and verifying the cylindricity tolerance of hinge bushings. A millesimal bore gauges was used to measure the internal diameter at different angular positions in each bushings’ sections. Starting from these measurements, the cylindricity of the inner surface of the bushing is evaluated through the least square cylinder (LSC) method. The angular deviation of the bushing axis is then evaluated based on the cylindricity assessment. The procedure allows to easily check, during assembly operations, whether the objects to be assembled are within tolerance without the need to resort to the most expensive and complex procedure through Coordinate Measuring Machines (CMM). Operation could be carried out on an assembly line by an operator using a pre-set spreadsheet.

Keywords: Angularity | Automotive Hinge | Circularity | Coaxiality | Cylindricity | Dimensions and Geometric Tolerances | Friction torque

Abstract: Parkinsons disease (PD) is the second most common progressive degenerative disease after Alzheimers disease, and occurs mainly in the population over 65 years of age. This disease, which is usually detected at an advanced stage, depends on a dysfunction of neuronal circuits comprising the motor cortical areas and the basal ganglia, resulting in movement abnormalities. This has a substantial impact on quality of life and requires various strategic treatments, including drug therapy, surgery and rehabilitation. This research work proposes a parametric multibody digital-twin model, developed in the Simulink-Simscape environment, capable of reproducing the posture and movements of PD patients. The model allows an accurate and non-invasive real-time or delayed assessment of patients’ movements, with the aim of identifying the main signs of disease progression at an early stage in order to prevent possible related risk factors and delay disease progression.

Keywords: Disease rating scale | Impaired motor control | Multibody digital-twin model | Neurodegenerative disease | Parkinsons disease

Abstract: This paper explores the influence of Voronoi tessellation parameters on the dynamic behavior of a mechanical tensioner's leaf spring used in internal combustion engines. By integrating Voronoi tessellation with Additive Manufacturing, the research investigates how varying the number of seeds affects the modal frequencies of the leaf spring. The study employs a design algorithm to maintain constant mass while adjusting the number of seeds and scaling factor, using a finite element (FE) formulation to predict and manage the leaf spring's dynamic nonlinear characteristics based on mass distribution. Modal simulations extract the natural frequencies, modal shapes, and participation factors of the component, analyzing how changes in these factors impact performance. The research findings underscore the significance of Voronoi parameters in modifying natural frequencies and dynamic behavior, highlighting their potential for topology optimization in frequency-sensitive applications. Validation comes through experimental testing, confirming the simulation results and emphasizing the role of appropriate mass distribution in controlling system frequencies.

Keywords: CAE Approach | Modal Frequencies | Participation Factors | Tensioner Leaf Spring | Topology Optimization

Abstract: No abstract available

Abstract: No abstract available

Abstract: Due to rapid socio-economic development, energy plays a fundamental role. Its constant supply is indispensable to ensure an adequate standard of living, currently met by non-renewable sources and close to exhaustion. In this scenario, hydrogen is very promising due to its ability to store large energy sources within its chemical bond and, unlike fossil fuels, is classified as a secondary energy carrier. Other forms of energy are needed for its production through electrolysis, to achieve a real energy transition. In this research work, a new type of compressor has been developed, whose operating principle is based on the fuel cells. This electrochemical device can be considered as an alternative method of hydrogen storage as it is able to compress low amounts of gas at high pressure. Given the low molecular weight of hydrogen and the desire to create stages with technically acceptable compression ratios, it is necessary to have very high peripheral speeds; this requires the choice of using materials with a high strength-to-specific gravity ratio.

Keywords: Electrochemical hydrogen compressor | Electrolysis | Energy consumption | Fuel cell | Hydrogen storage

Abstract: Renewable energy is an important objective that all sectors, such as engineering and architecture, must take into account during all phases of production and construction of products and buildings, in order to achieve sustainable development at a human, economic, social and environmental level. In fact, to face the challenges of climate change and ensure a cleaner and more sustainable future, it is necessary to adopt innovative approaches applied to sustainable energy, in order to revolutionize existing logics and reduce the negative impact on the environment and human health. The present research aims to provide an overview of the materials currently on the market, non-toxic and with remarkable eco-friendly characteristics, which are used in the redevelopment of existing buildings, in particular for the construction of green roofs.

Keywords: Climate change | Eco-friendly materials | Energy consumption | Environmental effects | Green roofs

Abstract: The increasing depletion of fossil fuels and their environmental impact have led to the development of fuel cell hybrid electric vehicles. By combining fuel cells with batteries, these vehicles offer greater efficiency and zero emissions. However, their energy management remains a challenge requiring advanced strategies. This paper presents a comparative study of two developed energy management strategies: a deterministic rule-based approach and a fuzzy logic approach. The proposed system consists of a proton exchange membrane fuel cell (PEMFC) as the primary energy source and a lithium-ion battery as the secondary source. A comprehensive model of the hybrid powertrain is developed to evaluate energy distribution and system behaviour. The control system includes a model predictive control (MPC) method for fuel cell current regulation and a PI controller to maintain DC bus voltage stability. The proposed strategies are evaluated under standard driving cycles (UDDS and NEDC) using a simulation in MATLAB/Simulink. Key performance indicators such as fuel efficiency, hydrogen consumption, battery state-of-charge, and voltage stability are examined to assess the effectiveness of each approach. Simulation results demonstrate that the deterministic strategy offers a structured and computationally efficient solution, while the fuzzy logic approach provides greater adaptability to dynamic driving conditions, leading to improved overall energy efficiency. These findings highlight the critical role of advanced control strategies in improving FCHEV performance and offer valuable insights for future developments in hybrid-vehicle energy management.

Keywords: battery | deterministic rules | energy management strategy | fuel cell | fuzzy logic | model predictive control

Abstract: A major challenge in constructing models of the human body or body parts stems from the fact that they are actually composed of several solid bodies articulated together. Consequently, 3D models must be parameterised with reference to joint angles: scans of the foot taken at different plantar/dorsal flexion angles were used in this study as a benchmark. The imple-mented methodology was based on the regression fitting of landmark trajectories obtained on a limited number of foot poses; these same landmarks were then used to guide 3D mesh morphing to predict foot geometry at different plantar/dorsal flexion angles. A careful optimi-sation of the methodology was performed to identify the optimal set of foot scans. The comparison between the actual foot shapes obtained by 3D laser scanning and the predicted shapes showed that the average error is at most 6.57 ± 2.74 mm. The methodology indications were finally drawn based on these error estimates. Further works will consider combined motions including flexion/extension, internal/external rotation, and foot inversion/eversion. © 2025 by the authors of this article.

Keywords: 3D laser scanner | 4D model | foot landmarks | mesh morphing | shape prediction

Abstract: In milling processes, an accurate prediction of surface roughness depending on the cutting parameters of the workpiece and the geometric profiles of the tool cutting edges can be decisive for high-quality and functional products. Roughness real value obtained at the end of the machining cannot be calculated analytically with extreme accuracy because in addition to depending on “basic” cutting parameters (feed rate, infeed, Z-pitch, spindle speed), it is influenced by numerous “complementary” parameters that significantly alter the theoretical value. Among these complementary parameters that show a greater influence were identified as follows: the degree of lubrication (lc), the mechanical and grain characteristics of the tool and the material (gc), tool wear (tw), the presence of vibrations (v), material inhomogeneity (mi), intrinsic material micro-imperfections (mmi), and unwanted interactions with the environment (Ei). In this research, through an analytical evaluation based on the basic cutting parameters and a machine learning (ML) regression approach according to the complementary parameters, an accurate prediction model of real surface roughness was developed. A classic K-Nearest Neighbor (kNN) algorithm, operating on seven dimensionalities of complementary parameters with a squared Euclidean metric, was trained from key performance indicators (KPIs) with a fairly populated dataset of experimental roughness measurements. Specifically, a “full factorial” dataset was selected, which evaluated all combinations of the first four complementary parameters (lc, gc, tw, v) for different processes and a “reduced factorial” for the remaining three parameters (mi, mmi, Ei). A pre-processing phase with adequate cleanup and integration of the training data has shown that the proposed methodology can provide a prediction accuracy of up to 99.06%. © The Author(s), under exclusive licence to Springer-Verlag London Ltd.

Keywords: Analytical roughness evaluation | Complementary parameters | Face milling machine | Machine learning | Peripheral milling machine

Abstract: Guardrails are designed to improve road safety by reducing the severity of accidents, preventing vehicles from leaving the roadway. 3D model studies could perform simulations that reproduce crash tests, considering the mechanical properties best suited to meet current regulations. This research illustrates a detailed behavior analysis of the individual constituent elements of the barriers and advances some improvements to be applied to their future development, evaluating a new guardrail with a greater elasticity given by a release device and a rhomboid spacer by analysing its dynamics and energy absorption during a road impact. Through experimental tests and FEM models, it was possible to determine the most significant parameters for the dynamic behavior of the new system, such as deformability, torsional and flexural stiffness. The progressive axial and flexural plastic collapse of the structure was studied by analysing the stress and strain states of the components reproducing, through a metal cylinder, the impact of a heavy vehicle with the guardrail at a speed of 3.5 m/s with impact angles of 20°, 45° and 90°. The proposed modifications to the guardrail increased the Acceleration Severity Index (ASI) by 10% and improved impact energy absorption by 39%, significantly reducing structural deformation. In light of the results, the proposed methodology allows the dynamic behavior of the rhomboidal spacer to be characterized through a limited number of experimental tests. In fact, the authors found in the scientific literature the lack of numerical-experimental methodologies to characterize and compare the elastoplastic behavior of different types of spacers.

Keywords: Crash test | Dynamic simulation | Guardrail | Impact performance | Rhomboid spacer | Road safety

Abstract: This study investigates the impact of Voronoi tessellation parameters on the dynamic behaviour of a leaf spring employed in a tensioner for internal combustion engine timing systems. The research utilizes a custom-developed algorithm to apply Voronoi tessellation while maintaining a constant mass by varying the number of seeds and scaling factors. Modal simulations were carried out to determine the natural frequencies, participation factors, and mode shapes of the component. These simulations were validated through experimental tests performed using a hammer impact test, which provided reliable and detailed measurements of the system’s dynamic response under different loading conditions. The experimental results revealed a strong correlation with the simulated data, demonstrating the accuracy of the proposed methodology. By modifying Voronoi tessellation parameters, it was possible to control and predict changes in natural frequencies and participation factors. These findings underscore the potential of Voronoi tessellation in dynamic system optimisation, enabling the design of components with tailored properties for improved performance. This research opens new avenues for integrating Voronoi-based design approaches with topology optimisation, particularly in the frequency domain, paving the way for innovative applications in mechanical and structural engineering.

Keywords: CAE approach | Modal frequencies | Optimal mass distribution | Participation factors | Tensioner leaf spring | Topology optimisation | Word

Abstract: The modernization of the information communication infrastructure of the regional data transmission network has advanced in order to increase the maximum transmission speed of existing transport routes, ensuring the quality of the service and its reliability. In the present research work, a new approach for the 3D visibility network algorithm has been developed, showing how graph theory applied to wireless sensor networks (WSNs) enables technological development for new solutions in areas such as public infrastructure. The possibility of determining in such networks whether an area of interest is sufficiently covered by a given set of sensors by means of the Voronoi diagram is discussed. The parking dynamics and parking system were modeled with cellular neural networks (CNNs) based on weather conditions, and magnetic parking sensors were replaced with pillar sensors. The proposed method has proven its effectiveness in determining the position of the minimum sensors covering the area of interest, in order to find a solution in the occupation of parking spaces in the presence of different weather conditions. The proposed approach and experimental results offer potential applications in various fields such as lighting and rendering, motion planning, pattern recognition, computer graphics and computational geometry, in order to conduct studies on problems and perspectives of pillar sensor technology while reducing costs compared to magnetic ones.

Keywords: 3D visibility network-graph | convolutional neural network | sensor network | voronoi diagrams | wireless networks algorithm

Abstract: The increase in dental diseases and the high demand for dental aesthetics in developed countries have favoured the growth of demand in the dental market for restorative treatments for damaged teeth and beyond. Today, modern prosthetic dentistry aims to find new materials whose biomechanical behaviour approximates that of natural enamel when subjected to functional loads. Computer-aided design, engineering and manufacturing (CAD-CAE and CAD-CAM) can provide new technologies for the design and production of dental devices. The aim of this research is to analyse the bio-mechanical behaviour of new materials such as zirconia and silica-based ceramics; the effects of functional loads on dental prostheses are examined, starting with the acquisition of a lower first molar with a Cone Beam Computed Tomography (CBCT) scan and the subsequent CAD design of a 3D model for the restoration. These technologies will enable the fabrication of dental structures with solid materials and/or cell structures characterised by variable anisotropy and porosity, providing patients with stable results over time. This will help minimise waiting times and production costs, as well as provide customised solutions of high precision and reduced invasiveness.

Keywords: Basic reconstruction materials | Biomechanical modelling | Dental devices | Mandibular kinematics | Prosthetic crown

Abstract: The miniaturization and integration of micro-electromechanical systems (MEMS) have progressively expanded the capabilities of advanced prosthetic hands, enabling not only the replication of human sensory and motor functions but also the implementation of sophisticated mechatronic control, precise manipulation, and adaptive responses to environmental interactions. The aim of this scoping review is to systematically map and evaluate current research on MEMS-integrated prosthetic hands, highlighting how MEMS sensors and mechanical modelling approaches contribute to dynamic control, biomechanical performance and user-centered functionality. Comparative analyses of different modelling techniques and MEMS applications indicate that MEMS-based sensing systems substantially improve the mechanical performance of prosthetic hands by enabling accurate force modulation, enhancing motion stability during dynamic tasks and supporting efficient signal acquisition for real-time control. These features lead to more precise control, smoother movements and enhanced dexterity during activities of daily living (ADL), broadening the functional capabilities of the devices. Microsurgical and neural interface aspects were also examined, including physiological considerations relevant to neural integration and common challenges related to prosthetic implantation, such as potential immunological responses to materials. The increasing role of MEMS in the development of smart, biomimetic prosthetic hands underscores new opportunities for creating highly adaptive devices, optimizing dexterity and environmental interaction and ultimately improving users’ quality of life.

Keywords: biomechanical modelling | dynamic control | mechatronic systems | MEMS sensors | prosthetic hand | smart hand prosthesis | smart MEMS

Abstract: This work is aimed to set-up a methodology for foot shape prediction at different flexion angles, overcoming limitations encountered when different poses are required but a limited set of acquisitions can be performed. The basic idea was to identify a fitting law able to interpolate positions of foot anatomical landmarks, and then use this information to guide the deformation of an average foot shape. First of all, mesh correspondence between foot geometries was accomplished by an established procedure based on mesh morphing. Then Procrustes analysis was applied to the dataset to remove rigid motions and estimate the average shape. Two interpolation laws (linear and quadratic) were investigated and the best one in terms of prediction of 3D landmarks’ coordinates was identified. Finally, shape geometries at any flexion angle were predicted performing a second mesh morphing guided by interpolated landmarks’ displacements from the average shape. These analyses proved that a limited number of interpolation angles provides a prediction accuracy comparable to that obtained using all the angles available in the dataset. Moreover, predicted shapes have been compared to the actual scans in terms of root mean square error between corresponding nodes, obtaining a mean value of 4.03 ± 1.39 mm, in accordance with data reported in literature.

Keywords: Accurate geometric reconstruction | Foot model | Real-time acquisition | Statistical deformation model | Statistical shape model

Abstract: Current technological developments in the field of sensor capture and additive manufacturing (AM) from computer models have led to innovative solutions for a 3D reconstruction of anatomical parts of the human body in real time, enabling interesting applications in the medical field and especially in orthopedics. The following work proposes the use of new technologies applied to tele-rehabilitation so that the patient can benefit from remote rehabilitation services. The wrist motion performed by the physical therapist was to be compared with the wrist motion of the patient undergoing rehabilitation, so as to obtain a proper analysis on the treatment to be followed, the expected timing and the recovery goals. Future applications could involve the use of the proposed system within hospitals and rehabilitation centers in order to support health care providers, improve patient care and quality of life, and contribute to the innovation of new approaches for medical assessment.

Keywords: Acquisition | Flexion-Extension | Radial-Ulnar deviation | Rehabilitation | Wrist

Abstract: Nowadays the interest for improving methodologies to design customized external devices for the neck has considerably grown, considered that neck pathologies are widespread among the population. Their design for additive manufacturing starts by acquiring the body’s part and, in order to achieve a satisfactory end result, the support of accurate reconstructed models from fast scans is relevant. At this aim, the availability of an average or statistical model could be potentially useful for reducing acquisition time and for upgrading low-resolution scans. This paper focuses on the application of a methodology for the creation of an average model of human neck. The method required the use of a set of scans, acquired by means of a structured light scanner, from which an accurate reconstruction of the neck surface was obtained. A number of healthy subjects of both genders was considered and the digital neck surfaces were used for creating an average digital model for males and for females. The methodology developed was based on mesh morphing and was applied to the sample considered with satisfactory results. The procedure is also suitable for the development of statistical models of the neck, that will cover future research

Keywords: Acquisition | Mesh morphing | Neck | Reverse Engineering

Abstract: This paper provides an up-to-date overview of the technologies used today in the field of Additive Manufacturing (AM). For each type of process, it is outlined which techniques are most often used and which are the most suitable materials for the development of the AM process. The latest technologies are analysed, highlighting their potential, accuracy and ability to create complex geometric features that are difficult, or impossible, to achieve by conventional processing techniques. Finally, some case studies developed by the authors dealing with lattice structures with high ratios of mechanical characteristics / porosity are presented. For these applications, the most proper AM technologies and the most performing materials, that provide accurate solutions, were evaluated.

Keywords: Additive Manufacturing | FDM techniques | High porosity | Lattice structures | Rapid Prototyping process

Abstract: Patients with spinal problems have difficulty when performing activities of daily living due to weakness or paralysis in the joints and muscular system, and this is a serious problem for people of all ages because it negatively affects their socio, physio, and economic lives. Traditional orthopedic corsets are a valuable support for these patients because these devices enable them to perform specific activities that require motor control, such as sitting, walking and other physical activities. However, they are often bulky, poorly ventilated and manufactured with non-biocompatible materials. This research focuses on the design and manufacturing of bespoke orthopedic corsets through a new organic bioplastic compound, optimizing the aspects of functionality, light weight, and small footprint. The developed orthosis offers design flexibility and improved porosity control, performing the functions of an exoskeleton, assisting patients with spinal problems who cannot be operated on because they have high risks during surgery, e.g., herniated disc, osteoporosis, injury, osteoarthritis, etc. It allows pain relief and the continuation of even the simplest activities of daily living making patients more independent. The most suitable materials, such as polymers and their composites, were evaluated to manufacture a customized and biodegradable orthosis. Future goals include automating the process of designing and printing the customized orthosis from a real-time scan of the patient's torso.

Keywords: Custom-made orthosis | Daily living activities | Orthopedic corset | Rehabilitation field | Wearable device

Abstract: The remarkable characteristics of polytetrafluoroethylene (PTFE) have made it one of the most widely used materials in various fields, especially in industry. PTFE has a low coefficient of friction, a high degree of anti-adhesive properties, excellent resistance to external agents, above all a high degree of resistance to low and high temperatures that guarantee long-lasting performance. In this research, a geometric dimensioning and tolerance (GD&T) and manufacturing methodology was presented to optimise the resistant torque in car doors hinges. The manufacturing technology of a PTFE-coated bronze bushing inserted with an FeZnNi pin inside the hinges of a car door was analysed and optimised. A predictive mathematical model was developed and validated with measurements using an appropriate experimental set-up created by the authors. Specifically, the experimental tests were performed by simulating and automating the rotation of the hinge, using software and electronic cards connected to an electric stepper motor; this made it possible to accurately assess the resistant torques due to assembly errors, tightening torques, geometric tolerances, etc. A correct assessment of the resistant torque and especially the friction torque is crucial, both at the design and production stages, to correctly calibrate the door drive loads (opening-closing), and to correctly predict the fatigue life of the components. Through the proposed methodology, the resistant torque was related to the correct manufacture and assembly of the hinge components.

Keywords: Bushing | FeZnNi pin | Friction torque | Geometric assembly tolerances | Hinges manufacturing | Polytetrafluoroethylene (PTFE)

Abstract: In recent years, additive manufacturing has been expanding rapidly in several sectors, including marine, aerospace and civil, offering broad design freedom and environmental/ecological advantages for the production of fully functional products. Particularly in the biomedical area, interesting manufacturing methods have recently been developed for the customisation of orthotic devices by automating the acquisition process and 3D printing. Today, in the development of complex geometries, it is necessary to meet certain design specifications, such as mechanical strength, surface finish, light weight, breathability and aesthetic appearance, which can potentially be met by manufacturing with 3D printers. This research deals with the development and implementation of organic bioplastic compounds based on polylactic acid (PLA) and organic by-products for additive manufacturing applications of customised orthotic parts. PLA, filled with reinforcements and additives, can be used to produce durable and functional parts for improved structural performance. By studying specific orthotic cases with CAD-CAE techniques, its potential mechanical properties will be evaluated and compared to highlight its performance comparable or even superior to that of classical PLA. The proposed methodology reduces production costs and environmental impact. Thanks to the presence of reinforcements and additives, the new organic bioplastic compounds are more biodegradable, while improving some of the functionality and comfort requirements of customised orthoses.

Keywords: biodegradability | biomedical orthosis devices | mechanical properties characterization | Organic bio-composite filament | Reverse Engineering

Abstract: In milling processes, an accurate prediction of surface roughness depending on the cutting parameters of the workpiece and the geometric profiles of the tool cutting edges can be decisive for high-quality and functional products. Roughness real value obtained at the end of the machining cannot be calculated analytically with extreme accuracy because in addition to depending on “basic” cutting parameters (feed rate, infeed, Z-pitch, spindle speed), it is influenced by numerous “complementary” parameters that significantly alter the theoretical value. Among these complementary parameters that show a greater influence were identified as follows: the degree of lubrication (lc), the mechanical and grain characteristics of the tool and the material (gc), tool wear (tw), the presence of vibrations (v), material inhomogeneity (mi), intrinsic material micro-imperfections (mmi), and unwanted interactions with the environment (Ei). In this research, through an analytical evaluation based on the basic cutting parameters and a machine learning (ML) regression approach according to the complementary parameters, an accurate prediction model of real surface roughness was developed. A classic K-Nearest Neighbor (kNN) algorithm, operating on seven dimensionalities of complementary parameters with a squared Euclidean metric, was trained from key performance indicators (KPIs) with a fairly populated dataset of experimental roughness measurements. Specifically, a “full factorial” dataset was selected, which evaluated all combinations of the first four complementary parameters (lc, gc, tw, v) for different processes and a “reduced factorial” for the remaining three parameters (mi, mmi, Ei). A pre-processing phase with adequate cleanup and integration of the training data has shown that the proposed methodology can provide a prediction accuracy of up to 99.06%.

Keywords: Analytical roughness evaluation | Complementary parameters | Face milling machine | Machine learning | Peripheral milling machine

Abstract: Additive manufacturing (AM) methods have a growing application in different fields such as aeronautical, automotive, biomedical, and there is a huge interest towards the extension of their use. In this paper, lattice structures for AM are analysed with regards to stiffness and printability in order to verify the suitability for applications where the main requirement of efficiency in terms of stiffness has to be balanced with other needs such as weight saving, ease of manufacturing and recycling of the material. At this aim, lattice structures with high porosity unit cells and large cell size made of a recyclable material were considered with a geometrical configuration allowing 3D printing without any supports. The lattice structures considered were based on body-centred cubic (BCC) and face centred cubic (FCC) unit cell combined with cubic cell. Finally, a multi-morphology lattice structure obtained by mixing different unit cells is also proposed. The lattice structures were modelled and structurally analysed by means of finite element method (FEM), manufactured with a Fusion deposition modelling (FDM) printer and evaluated in relation to printability and dimensional accuracy. The results show that the proposed structure with mixed cells is potentially advantageous in terms of weight saving in relation to the mechanical properties.

Keywords: Additive manufacturing | Geometrical configuration | High porosity | Lattice structure | Supportless 3D printing

Abstract: Analyzing pathological movements can substantially help neurologists in the diagnosis and treatment improvement for patients with Parkinson’s disease (PD). A linkage between the intensity and characteristics of moving and walking disorders and the stage and types of PD can be actually established. The main aim of this study is to develop an effective methodology that allows to evaluate, in real time and / or in deferred time, movements and posture of PD patients in their usual living environments. For this purpose, a wearable suit with Inertial Measurement Unit (IMU) sensors was designed; it has made it possible to acquire linear and angular signals of displacement, velocity and acceleration of the most relevant body points of the patients. The filtered and integrated signals were then used to animate a human parametric multibody model that virtually reproduces in real time and / or in deferred patient’s movements and posture. Serving as the patient's “avatar”, the multibody model enables the neurologist to carry out an accurate assessment of the patient’s movements and posture (freezing, festination, postural balance) as well as to measure disease progression and response to interventions. If compared to traditional 3D video-based motion analysis systems, the proposed method has the advantage of providing a more accurately measurable patients movements analysis and comparison performed in their usual living environments in real-world conditions.

Keywords: 3D posture analysis | Human parametric multibody model | Inertial Measurement Unit sensors | Motion recognition algorithms | Parkinson’s disease movements

Abstract: The dynamic behavior of a Powered Two-Wheeler (PTW) is much more complicated than that of a car, which is due to the strong coupling between the longitudinal and lateral dynamics produced by the large roll angles. This makes the analysis of the dynamics, and therefore the design and synthesis of the controller, particularly complex and difficult. In relation to assistance in dangerous situations, several recent manuscripts have suggested devices with limitations of cornering velocity by proposing restrictive models. However, these models can lead to repulsion by the users of PTW vehicles, significantly limiting vehicle performance. In the present work, the authors developed an Advanced Rider-cornering Assistance System (ARAS) based on the skills learned by riders running across curvilinear trajectories using Artificial Intelligence (AI) and Neural Network (NN) techniques. New algorithms that allow the value of velocity to be estimated by prediction accuracy of up to 99.06% were developed using the K-Nearest Neighbor (KNN) Machine Learning (ML) technique.

Keywords: advanced rider assistance systems | k-nearest neighbor | machine learning | maximum cornering velocity | powered two-wheeler dynamic behavior

Abstract: Aim of all designers is to optimize the product principally in term of mass. The classic manufacturing processes constraint the designer to use a limited number of parameters for obtaining the best results. New manufacturing processes like Additive Manufacturing, open the way to a new optimization strategies, one of the most important is the topology optimization. The objective function is to reduce the mass keeping other functionalities of the product intact. The starting geometry of each topology optimization can be the geometry used for the classic manufacturing method or it can be the lattice structure or a geometry with a tessellation applied by means Voronoi technique. Aim of this paper is to investigate the potential of Voronoi tessellation in the field of structural engineering. A titanium plate with Voronoi tessellation is modelled varying the number of seeds and keeping the total mass unaltered. Thanks to a finite element simulation, for each condition a modal analysis has been performed and the natural frequencies have been extracted. The paper discusses about the influence of the number of seeds to the natural frequencies of plate. This could be a new way and a starting point for topology optimization oriented to the management of natural frequency domain exploiting the Voronoi parameters.

Keywords: CAE approach | Design for additive manufacturing | Topology optimization

Abstract: The largest contribution of electricity production comes from conventional sources including coal and oil that pollute the environment. Renewable energy sources, including solar energy, wind energy and energy storage in batteries, are expected to play a progressively central role in meeting future energy needs in all sectors, largely responding to the increasing demand for energy. In particular, the use of solar energy will be considered as the main solution to global climate change and fossil fuel emissions. Although today's photovoltaic panels have an average lifespan of 25 years, their disposal is a cause for concern when photovoltaic technology is evaluated from the perspective of comprehensive life cycle analysis and End-of-Life management (EoL). We therefore need some innovative solutions that can reduce emissions of pollutants as a result of the recycling of solar panels that no longer work. This manuscript reports some of the most current efficient and effective photovoltaic (PV) panel recycling solutions and the foreseeable developments for such recycling.

Keywords: EcoDesign | End-of-life management | Photovoltaic panels | Renewable resources | Sustainability

Abstract: An area of interest in orthopaedics is the development of efficient customized neck orthoses, considered that pathologies which affect the neck area are widespread. Advanced acquisition and modelling approaches combined with Additive Manufacturing (AM) can potentially provide customized orthoses with improved performance and complexity. However, in the design of these devices, besides functional and structural requirements, benefit and comfort of the patient should be a main concern, in particular, at the early stage of design during the acquisition of the body’s part, and while using the printed orthosis. In this paper, a scanning system with three sensors was developed which allows a fast, about 5 s, and accurate acquisition of the neck area with minimum discomfort for the patient. A neck orthosis with a ventilation pattern obtained by Topology Optimization (TO), lightened by about 35%, was also established. In fact, a main role for comfort is played by the ventilation pattern which contributes both to lightness and breathability. Its structural and comfort performance was evaluated in comparison with an orthosis with a ventilation pattern configured by Voronoi cells. Structural assessment was carried out by means of finite element analysis under main loading conditions. An evaluation of neck temperatures in relation to wearing 3D printed prototypes, manufactured with Hemp Bio-Plastic® filament, was finally conducted by means of a thermal imaging camera. TO orthosis prototype showed a better performance regarding thermal comfort, with a maximum increase of neck temperature less than 1 °C, which makes the proposed configuration very promising for user's comfort.

Keywords: Additive manufacturing | CAD | Orthosis modelling | Reverse engineering | Thermal comfort | Topology optimization

Abstract: The analysis of motor activity has been revealed to be essential for monitoring dairy cows’ behavior, with the main aim of identifying the onset of oestrus in time. Pedometers used for oestrus detection have a current average working life on the market of about 5 years. At the end of that period, devices are disposed of, posing a relevant question regarding environmental sustainability. The present work proposed a method to achieve an eco-design of pedometers compliant with the guidelines of the Green Deal. Specifically, a new thermo-plastic organic compound made of polyamide 66 reinforced with organic hemp fibers (trade name SDS Nylon) was adopted. The feasibility, benefits, and performance of this material were assessed with a major emphasis on strength, lightweight, and surface finish. The material in addition to ensuring adequate chemical and mechanical resistance is biocompatible and recyclable. It assures better animal welfare and reduces both environmental impacts and management costs for farmers. Other innovations introduced in this study consisted of the adoption of a double casing. An external case was conceived with a protective function of the measurement system and fixed to a cow’s foreleg by an easy anchor system. An internal case was specifically designed to house the electronic components and to be moved from one cow to another after the pregnancy diagnosis. The solutions proposed in this research will contribute to guaranteeing pedometers a longer lifetime and better recyclability than existing commercial ones, consequently limiting the environmental load derived from their disposal.

Keywords: biocompatible materials for FDM | custom design | digital product optimization | stand-alone smart device | tolerances assignment

Abstract: There is a large body of research devoted to identifying the complexity of structures in networks. In the context of network theory, a complex network is a graph with nontrivial topological features—features that do not occur in simple networks, such as lattices or random graphs, but often occur in graphs modeling real systems. The study of complex networks is a young and active area of scientific research inspired largely by the empirical study of real-world networks, such as computer networks and logistic transport networks. Transport is of great importance for the economic and cultural cooperation of any country with other countries, the strengthening and development of the economic management system, and in solving social and economic problems. Provision of the territory with a well-developed transport system is one of the factors for attracting population and production, serving as an important advantage for locating productive forces and providing an integration effect. In this paper, we introduce a new method for quantifying the complexity of a network based on presenting the nodes of the network in Cartesian coordinates, converting to polar coordinates, and calculating the fractal dimension using the ReScaled ranged (R/S) method. Our results suggest that this approach can be used to determine complexity for any type of network that has fixed nodes, and it presents an application of this method in the public transport system.

Keywords: complexity | fractal | Hurst exponent H | network | public transport

Abstract: In this paper an interactive computational methodology was developed assuming that shape and size optimization of flexible components can significantly improve energy absorption or storage ability in assembled systems with flexible components (AS-FC). A radial basis functions mesh morphing formulation in non-linear numerical finite element analysis, including contact problems and flow interaction, was adopted as optimal design method to optimize shape and size design parameters in AS-FC. Flexible components were assembled in finite element environment according to functional ISO-ASME tolerances specification; non-linear structural analysis with flow interaction analysis was performed. The results of the study showed that the proposed method allows to optimize the shape and size of the flexible components in AS-FC maximizing the system's ability to absorb or store energy. The potentiality of the method and its forecasting capability were discussed for the case study of an automotive crash shock in which the specific energy absorption was increased by over 40%. The case studied refers to a simple flexible component geometry, but the method could be extended to systems with more complex geometries.

Keywords: Crash shock absorber | ISO-ASME tolerances specification | Radial basis functions | Shape and size optimization | Specific energy absorption

Abstract: Nowadays, laser hardening is a consolidated process in many industrial sectors. One of the most interesting aspects to be considered when treating the surface-hardening process in steel materials by means of laser devices is undoubtedly the evaluation of the heat treatment quality and surface finish. In the present study, an innovative method based on fractal geometry was proposed to evaluate the quality of surface-steel-laser-hardened treatment. A suitable genetic programming study of SEM images (1280 × 950 pixels) was developed in order to predict the effect of the main laser process parameters on the microstructural geometry, assuming the microstructure of laser-hardened steel to be of a structurally complex geometrical nature. Specimens hardened by anthropomorphic laser robots were studied to determine an accurate measure of the process parameters investigated (surface temperature, laser beam velocity, laser beam impact angle). In the range of variation studied for these parameters, the genetic programming model obtained was in line with the complexity index calculated following the fractal theory. In particular, a percentage error less than 1% was calculated. Finally, a preliminary study of the surface roughness was carried out, resulting in its strong correlation with complex surface microstructures. Three-dimensional voxel maps that reproduce the surface roughness were developed by automating a routine in Python virtual environment.

Keywords: 3D voxel map | Fractal geometry | Genetic programming | Laser beam process parameters | Surface roughness

Abstract: Numerical codes can play an important function in the nautical design when advanced simulation tools are increasingly adopted for prediction purposes, and in particular for the calculation of the interaction between boat parts and surrounding fluids. Fluid-structure interaction analysis (FSI) can help engineers to set the optimum design of a sail and also the influence of panels and battens sail arrangement. The paper describes a methodology that enhances the understanding of panel and battens arrangement, as well as their stiffness on sail performance. Specifically, through the battens position, shape and stiffness parametrization, the sail non-developable shape was optimized, in order to compensate the variation in the angle of attack that occurs following variations in the speed of the wind at different sail heights. For an efficient and robust implementation of integrated Reynolds Averaged Navier Stokes (RANS) equations with Shear Stress Transport (SST) turbulence model and Computational Structural Mechanics (CSM) analysis, the constitutive sailcloth and battens characterization was conducted experimentally. The case study of a mainsail in Dacron© TNF 240 of a Vaurien dinghy boat, offered tangible results to support the methodology by validating it with experimental data.

Keywords: CFD-CSM analysis | Flying shape | Sail battens arrangement | SST model | Triangular membrane modeling | Twisting

Abstract: The use of additive manufacturing (AM) has widespread over the years in different areas, including the biomedical field. In particular, the design of customized orthoses, external medical devices used in the treatment of specific pathologies, was proposed in different studies mainly concerning upper limbs, while few investigations are reported relatively to the cervical area. In this paper a new design of a bespoke neck orthosis is reported. The manufacturing of a light device with a good transpiration allows to increase the patient’s comfort and, compatibly with the structural requirements, is a main goal to pursue. With this aim, various aspects were considered in the design and manufacturing of the orthosis. At the design stage, the geometry was conceived with a ventilation pattern based on Voronoi cells, which generally allows a better performance in terms of breathability with respect to a pattern made with uniform geometrical features, keeping at the same time structural requirements, as assessed by numerical finite elements simulations. At the manufacturing stage, a new composite material was used, namely Hemp Bio-Plastic® (HBP) filament, composed by polylactic acid (PLA) and hemp shives which provided lightweight, improved superficial finish and antibacterial properties. In order to assess the thermal comfort, an experimental analysis was finally conducted on a prototype of the orthosis, worn by a volunteer subject, with a thermal imaging camera. The beneficial effect of the ventilation pattern considered in terms of temperature and, accordingly, for the patient’s comfort, was highlighted also in relation to a neck orthosis previously designed.

Keywords: Additive manufacturing | Bio-composite | Orthosis modeling

Abstract: The production of electric energy has been increasingly deriving from renewable sources, and it is projected that this trend will continue over the next years. Among these sources, the use of solar energy is supposed to be considered the main future solution to global climate change and fossil fuel emissions. Since current photovoltaic (PV) panels are estimated to have an average life of 25–30 years, their disposal is very important for the recovery of materials already used and for introducing them again into other processing cycles. Innovative solutions are therefore needed to minimize the emissions of pollutants derived from the recycling of photovoltaic panels that no longer work. In this research, an analysis of data related to durability, recyclability rates, different possible design layouts and materials used in the design and manufacture of PV panels was conducted. Through a Design for Recycling (DfR) and a Design for Durability (DfD), the authors identified the optimal materials, the best geometries and geometric proportions as well as the most convenient geometric and dimensional tolerances in the couplings between the layers and the components that comprise the panel to attain the most current, efficient and effective solutions for recycling end-of-life (EoL) PV panels and for longer durability

Keywords: coupling tolerances | EcoDesign method | end-of-life management | recyclability rates | sustainability

Abstract: This research concerns the optimization study of the wing of an ultralight competition sailplane, category F5J/F3J. Fundamental for this category is the characteristic of lightness associated with good wing stiffness (bending/torsional). All the elements composing the wing of the sailplane were modelled in 3D by using the Autodesk Inventor parametric solid modeler. They were assembled in the FEM environment and were suitably constrained and studied from a structural point of view. The structural characteristics of the wing and its components were analysed in detail after assigning the materials currently used and adopting appropriate materials to make the same with the Additive Manufacturing (AM) technic. A topological optimization, performed by using the Simplex Method (SIMP), was conducted on the internal structure of the wing in order to lighten the ribs with the same performance. The experimental investigations implemented in the laboratory allowed the ’Oralight’ material used for the wing surface coating to be characterized. It is an extremely thin and light material, whose elasticity and strength were accurately assessed in this study. The data obtained, considered along with the elasticity and the resistance values of the other materials constituting the wing structure, taken from the literature, were inserted into the finite element simulations with the aim of evaluating the torsional and bending stiffness of the wing. Finally, the rib was redesigned using a FDM material which makes construction particularly simple.

Keywords: Oralight Coating Surface | Compound Bio-Plastic Filament | Ribs and Spars’ Redesign | Torsional and Bending Wing Stiffness | Wing Parametric Modelling

Abstract: The paper illustrates the design of a new mechanical system for propeller blades pitch calibration in medium power wind turbines. The peculiarity of this system is its capacity of adjusting through a feedback control system, which allows the wind turbine to capture the maximum amount of energy from the wind. In this work an axial drive system was studied by means of racks capable of linearly adjusting the pitch of all wind turbine propeller blades in an intrinsically synchronous way, with an advantage over the traditional methods of propeller blades pitch calibration. For different wind speeds the system adjusts the blades angle of incidence in order to reduce the rotation speed and keep the system as close as possible to the pre-established design conditions generating maximum energy with a high efficiency. The manuscript examines the main analyses and simulations conducted during the design phase. These show that the proposed method allows to reach higher efficiencies with a greater intrinsic stability compared to the traditional pitch control mechanisms in medium power wind turbines. The experimental results on the first prototypes confirm the efficiency increase.

Keywords: Linearly Adjusting | Medium Power Wind Turbines | Pitch Calibration | Propeller Blades | Racks

Abstract: This paper investigates improving the quality of the energy used in the railway field. Due to structural aspects, the railway substations of the high-speed lines generate a voltage imbalance, polluting the electric power. To solve this unbalance problem, a new structure of unbalance compensation based on the concept of impedance controller by Ac-chopper was introduced. This new strategy's dimensioning and control were based on real data provided by the Moroccan national railway operator ONCF. To prove that this solution has a significant impact on the treatment of the unbalance phenomenon and that the CCI compensator behaves like an Eco-design due to its constitution and the reduction of power losses, a comparison was established with the topologies using a Voltage Source Inverter (VSI) and Current Source Inverter (CSI) in terms of energy loss in the semi-conductors; the modelling of the three structures was performed under the MATLAB Simulink environment. The results showed that the CCI compensator is more efficient in limiting the unbalance problem than the other compensators (VSI and CSI). © 2022 Praise Worthy Prize S.r.l.-All rights reserved.

Keywords: Concept of AC-Chopper Controlled Impedance | Optimization Electric Power | Railway | STATCOM

Abstract: This Special Issue of Applied Sciences provides a collection of original papers on smart manufacturing technology with the aim of: examining emerging aspects of digitalization in the industrial and biomedical fields, as well as in business management and sustainability; proposing and developing a new approach useful for companies, factories, and organizations to achieve greater innovation and productivity—as well as sustainability—by applying smart manufacturing technologies; and exploring new ideas and encouraging research directions so as to obtain autonomous and semiautonomous processes, high-quality products, and services with a greater integration and interconnection of resources while reducing costs. The advantages of new methods and experimental results obtained in the collected contributions are discussed promoting further design, implementation, and application in the various fields.

Keywords: Assessment of digitalization | Computational geometry and CAD/CAM | Enabling technologies | Machine learning | Machine tools and manufacturing equipment | Manufacturing networks and security | Sustainability | Virtual/augmented reality

Abstract: Principal components analysis is a powerful technique which can be used to reduce data dimensionality. With reference to three-dimensional bone shape models, it can be used to generate an unlimited number of models, defined by thousands of nodes, from a limited (less than twenty) number of scalars. The full procedure has been here described in detail and tested. Two databases were used as input data: the first database comprised 40 mandibles, while the second one comprised 98 proximal femurs. The “average shape” and principal components that were required to cover at least 90% of the whole variance were identified for both bones, as well as the statistical distributions of the respective principal components weights. Fifteen principal components sufficed to describe the mandibular shape, while nine components sufficed to describe the proximal femur morphology. A routine has been set up to generate any number of mandible or proximal femur geometries, according to the actual statistical shape distributions. The set-up procedure can be generalized to any bone shape given a sufficiently large database of the respective 3D shapes.

Keywords: 3D model generator | Comparative anatomy | Mandible anatomy | Mesh morphing | PCA | Proximal femur anatomy | Stochastic bone models

Abstract: In this research, we describe a computer-aided approach to improve the reconstruction method of decorum in architectural surfaces and sculpture. The effects of withdrawal caused by catalysis of mold in silicone was evaluated and simulated by a NURBS-based solid modelling. A tolerance analysis model was developed to predict manufacturing precision levels. In particular, differential increment along three dimensions was performed considering different volume distributions. The methodology was validated by experimental data obtained during the coffered ceiling restoration of Teatro Massimo Vittorio Emanuele in Palermo. The proposed methodology allowed the reconstruction of decorations or fragments of decoration with high accuracy.

Keywords: Geometric dimensioning and tolerancing | Restoration techniques | Reverse engineering | Silicon mold | Withdrawal

Abstract: The tyre-suspension-seat dynamic system, driveline and engine vibrations are generally considered in the vibrational field as the main factors that influence the particular feeling of comfort perceived by passengers on a vehicle. Hence, the development of several criteria and models for the optimal estimation of the design parameters of such systems. Among these parameters, the most detrimental impacting on the passenger comfort are undoubtedly acceleration and its variation. The two types of suspension systems (conventional passive suspension system and active suspension system) differ as the first foresees the spring-damper characteristics to be adjusted so that only one of several conflicting objectives (such as passenger comfort, road holding, and suspension deflection) is followed. In active suspension systems, instead, these objectives are balanced by the designer in a more efficient manner thanks to the feedback-controller actuator assembly. However, this approach presents some limitations linked to the extremely wide spectrum of magnitude and frequency of external forces that the tyre-suspension-seat system has to efficiently control and mitigate. It remains that in the existing optimisation models and systems time exposure limits established by unification agencies and road authorities are not generally considered. This paper illustrates the development of an active tyre-suspension-seat system control for passenger cars, using both a non-linear multibody model and Genetic Algorithm (GA) controls. A benefit of the proposed active tyre-suspension-seat system control is also to consider various time exposure limits and an active damping element. The main innovative element introduced by this work consists in having coupled an active control to passive mechanical parameters in order to minimize the seat acceleration. The 3 DoF multibody model, applied to a quarter body for symmetry reasons, treated road roughness as an input variable in the GA control so as to determine the vertical component of acceleration. The numerical and experimental applications of the proposed model to a specific case study allowed to validate the effectiveness of the active system towards the vibrations transmitted to the passenger.

Keywords: Acceleration variation | Active suspension system | Genetic algorithm | Passenger comfort | Vibrations

Abstract: Surface-hardening process of steel materials by robot laser technologies can involve the challenge of modeling the determining process parameters through non-conventional tools in order to evaluate the quality of the heat treatment. In the current study a new method based on fractal geometry, used to determine the microstructural properties of laser hardened steels manufactured by anthropomorphic robots, is presented. The assumptions were that the microstructure of laser hardened steel can be studied as a complex structural geometry and the modeling of the analyzed complex geometries can be made through genetic programming for prediction purposes. The effect of process parameters and their joint combination on the final microstructures geometry of the heat treated steel was investigated. In particular, the influence of temperature, laser beam velocity, and impact angle were studied since they were showed in a preliminary study to be the process parameters that most significantly influenced the quality of the heat treated steel. The developed model reached a precision of the prediction equal to 98.59 %.

Keywords: Forecast model | Fractal geometry | Hardened steels | Laser beam process parameters | Microstructure geometry

Abstract: Traditional analytical methods are approximate and need to be validated when it comes to predict the tensional behavior of thread coupling. Numerical finite element simulations help engineers come up with the optimum design, although the latter depends on the constraints and load conditions of the thread couplings which are often variable during the system functioning. The present work illustrates a new method based on Radial Basis Functions Mesh Morphing formulation to optimize the stress concentration in thread couplings which is subject to variable loads and constraints. In particular, thread root and fillet under-head drawings for metric ISO thread, which are the most commonly used thread connection, are optimized with Radial Basis Functions Mesh Morphing. In metric ISO threaded connection, the root shape and the fillet under the head are circular, and from shape optimization for minimum stress concentration it is well known that the circular shape becomes seldom optimal. The study is carried out to enhance the stress concentration factor with a simple geometric parameterization using two design variables. Radial Basis Functions Mesh Morphing formulation, performed with a simple geometric parameterization, has allowed to obtain a stress reduction of up to 12%; some similarities are found in the optimized designs leading to the proposal of a new standard. The reductions in the stress are achieved by rather simple changes made to the cutting tool.

Keywords: Feature-based modeling | Fillet under-head | Metric ISO thread | Radial basis functions | Thread root

Abstract: Laryngoscopes are used as diagnostic devices for throat inspection or as an aid to intubation. Their blade must be geometrically compatible with patients’ anatomy to provide a good view to doctors with minimal discomfort to patients. For this reason, this paper was aimed to investigate the feasibility of producing customized blades. The customizable blade model was developed following a feature-based approach with eight morphological parameters. The thickness of such a blade was determined through numerical simulations of ISO certification tests, where the finite element mesh was obtained by morphing a ‘standard’ mesh. The following procedure was applied: the model was built from the selected parameters; the blade was tested in silico; finally, the blade was produced by additive manufacturing with an innovative biodegradable material (Hemp Bio-Plastic® -HBP-) claimed to feature superior mechanical properties. The procedure evidenced that the mechanical properties of current biodegradable materials are unsuitable for the application unless the certification norm is revised, as it is expected.

Keywords: Additive manufacturing | Biodegradable materials | Feature-based modeling | Laryngoscope blades | Mesh-morphing | Parametric drawing | Patient-specific design

Abstract: Alluvial (torrential) fans, especially those created from debris-flow activity, often endan-ger built environments and human life. It is well known that these kinds of territories where human activities are favored are characterized by increasing instability and related hydrological risk; there-fore, treating the problem of its assessment and management is becoming strongly relevant. The aim of this study was to analyze and model the geomorphological aspects and the physical processes of alluvial fans in relation to the environmental characteristics of the territory for classification and prediction purposes. The main geomorphometric parameters capable of describing complex properties, such as relative fan position depending on the neighborhood, which can affect their formation or shape, or properties delineating specific parts of fans, were identified and evaluated through digital elevation model (DEM) data. Five machine learning (ML) methods, including a hybrid Euler graph ML method, were compared to analyze the geomorphometric parameters and physical characteristics of alluvial fans. The results obtained in 14 case studies of Slovenian torrential fans, validated with data of the empirical model proposed by Bertrand et al. (2013), confirm the validity of the developed method and the possibility to identify alluvial fans that can be considered as debris-flow prone.

Keywords: Debris flows | Digital elevation model | Geomorphometric parameters | Graph method | Torrential fan surfaces

Abstract: In the article titled “Design of Additively Manufactured Lattice Structures for Biomedical Applications” [1], there was an error in the author’s name, where “Sverio Maietta” should be corrected to “Saverio Maietta.” e corrected author name is shown in the author group above.

Abstract: Rail–wheel interaction is one of the most significant and studied aspects of rail vehicle dynamics. The vibrations caused by rail–wheel interaction can become critical when the radial, lateral and longitudinal loads of the vehicle, cargo and passengers are experienced while the vehicle is in motion along winding railroad paths. This mainly causes an excessive production of vibrations that may lead to discomfort for the passengers and shortening of the life span of the vehicle’s body parts. The use of harmonic response analysis (HRA) shows that the wheel experiences high vibrational amplitudes from both radial and lateral excitation. The present study describes a numerical and experimental design procedure that allows mitigation of the locomotive wheel resonance during radial and lateral excitations through viscoelastic layers. It is proven that these high frequencies can be reduced through the proper design of damping layer mechanisms. In particular, three parametric viscoelastic damping layer arrangements were analyzed (on the web of both wheel sides, under the rim of both wheel sides and on the web and under the rim of both wheel sides). The results demonstrate that the correct design and dimensions of these viscoelastic damping layers reduce the high-amplitude resonance peaks of the wheel successfully during both radial and lateral excitation.

Keywords: harmonic response analysis | lateral excitation | modal analysis | radial excitation | viscoelastic damping layers | web and rim parametric design

Abstract: The present work illustrates the dynamization of an orthopaedic plate for internal fracture fixation which is thought to shorten healing times and enhance the quality of the new formed bone. The dynamization is performed wirelessly thanks to a magnetic coupling. The paper shows the peculiarities of the design and manufacturing of this system: it involves two components, sliding with respect to each other with an uncertain coefficient of friction, and with a specific compounded geometry; there are stringent limits on component size, and on the required activation energy. Finally, the device belongs to medical devices and, as such, it must comply with the respective regulation (EU 2017/745, ASTM F382). The design of the dynamizable fracture fixation plate has required verifying the dynamic of the unlocking mechanism through the development of a parametric multibody model which has allowed us to fix the main design variables. As a second step, the fatigue strength of the device and the static strength of the whole bone-plate system was evaluated by finite element analysis. Both analyses have contributed to defining the final optimized geometry and the constitutive materials of the plate; finally, the respective working process was set up and its performance was tested experimentally on a reference fractured femur. As a result of these tests, the flexural stiffness of the bone-plate system resulted equal to 370 N/mm, while a maximum bending moment equal to 75.3 kNmm can be withstood without plate failure. On the whole, the performance of this dynamic plate was proved to be equal or superior to those measured for static plates already on the market, with excellent clinical results. At the same time, pre-clinical tests will be an interesting step of the future research, for which more prototypes are now being produced.

Keywords: Dynamizable plate | Fracture synthesis | Internal fixation | Mechanical tests | Medical device manufacturing | Stress analysis

Abstract: The most recent developments of Fused Deposition Modelling (FDM) techniques are moving the application of Additive Manufacturing (AM) technologies toward new areas of investigation such as the biomedical, aerospace, and marine engineering in addition to the more consolidated industrial and civil fields. Some specific characteristics are required for the components designed for peculiar applications, such as complex geometries, lightweight, and high strength as well as breathability and aesthetic appearance specifically in the biomedical field. All these design specifications could be potentially satisfied by manufacturing with 3D printing techniques. Moreover, the development of purpose-dedicated filaments can be considered a key factor to successfully meet all the requirements. In this paper, fabrication and applications of five new thermoplastic materials with fillers are described and analyzed. They are organic bio-plastic compounds made of polylactic acid (PLA) and organic by-products. The growing interest in these new composite materials reinforced with organic by-products is due to the reduction of production management costs and their low environmental impact. In this study, the production workflow has been set up and described in detail. The main properties of these new thermoplastic materials have been analyzed with a major emphasis on strength, lightweight, and surface finish. The analysis showed that these materials can be particularly suitable for biomedical applications. Therefore, two different biomedical devices were selected and relative prototypes were manufactured with one of the analyzed thermoplastic materials. The feasibility, benefits, and performance of the thermoplastic material considered for these applications were successfully assessed.

Keywords: Additive manufacturing capability | Biomedical applications | Design | Mechanical properties | Organic bio-composite filament | Roughness

Abstract: Current Fused Deposition Modelling (FDM) techniques have promoted the extension of 3D printing technologies to new applications ranging from the biomedical, aerospace, and submarine fields, to some specific applications in manufacturing and civil fields. The expansion of the fields of application, generally, entails considering peculiar characteristics, such as complex geometries or requirements as low density. Furthermore, the breathability, the pleasantness to the touch, aesthetic appearance and a strong visual identity, that can be achieved by means of 3D printing, are especially requested for some applications such as biomedical. For the improvement of the manufacturing of these parts, the design of a dedicated filament is a relevant issue to be taken into account. polylactic acid (PLA) and organic by-products from agricultural waste. The study includes a preliminary illustration of the main properties of these materials and a biomedical application of such bio-plastic compounds through experimental testing in order to assess the suitability to FDM printing. In particular, the performance in terms of lightweight, strength and roughness have been evaluated. The interesting final properties make these materials suitable for biomedical applications as it is shown in this study for the neck collar prototype reported. In addition, such innovative bio-composite materials allow reducing the cost of environmental impact as well as the production management costs.

Keywords: Additive manufacturing capability | Bio-plastic compounds | Biomedical applications | Mechanical properties | Organic bio-composite filament | Roughness

Abstract: This paper discusses an approach developed for exploiting the local elementary movements of evolution to study complex networks in terms of shared common embedding and, consequently, shared fractal properties. This approach can be useful for the analysis of lung cancer DNA sequences and their properties by using the concepts of graph theory and fractal geometry. The proposed method advances a renewed consideration of network complexity both on local and global scales. Several researchers have illustrated the advantages of fractal mathematics, as well as its applicability to lung cancer research. Nevertheless, many researchers and clinicians continue to be unaware of its potential. Therefore, this paper aims to examine the underlying assumptions of fractals and analyze the fractal dimension and related measurements for possible application to complex networks and, especially, to the lung cancer network. The strict relationship between the lung cancer network properties and the fractal dimension is proved. Results show that the fractal dimension decreases in the lung cancer network while the topological properties of the network increase in the lung cancer network. Finally, statistical and topological significance between the complexity of the network and lung cancer network is shown.

Keywords: Bioengineering | Complex networks | DNA geometry | Fractal dimension | Topological properties

Abstract: High fidelity calculation tools are well established in the nautical design sector where advanced numerical simulations are adopted for the prediction of the interaction of boat parts with surrounding fluids. The capability to couple such tools with efficient shape parametrization procedures offers the possibility to further improve the performance speeding up the design process. Radial Basis Functions (RBF) Mesh Morphing (MM) allows to quickly modify the shape within numerical domains without the need of updating the underlying CAD representation. The validity of this approach, widely adopted in aeronautical and automotive fields, is demonstrated in this paper by applying the method to the analysis of the flying shape of a symmetric spinnaker also investigating the importance of panel arrangement on sail characteristics. The performance, in terms of drive and side forces, is evaluated for different morphed geometries by RANS (Reynolds Averaged Navier Stokes) analyses. The RBF setup proved to be efficient and robust in generating a good quality of the morphed domain within the full range of amplification from the undeformed to the flying shape geometry.

Keywords: Drive and side force | Geometric parametrization | Mesh morphing | Radial basis functions | RANS analysis | Symmetric spinnaker

Abstract: This paper proposes a replicable methodology based on virtual prototyping design in multibody environment to optimize the functionality of Mechanical Spring Devices (MSD). These devises are assembled to control the shaft angular velocity in medium-voltage (MV) switch disconnector. The angular velocity of switch disconnector, moving the contact fingers, is directly linked to arcing time, which is the parameter that mainly influences accuracy, safety drives and a longer service life of device. Design of experiment (DoE) techniques, integrated with tridimensional geometric parametrization, were used in multibody environment to optimize the displacement of switch disconnector shaft. The best values of shape, stiffness and preload of the main cylindrical helical spring of MSD were obtained in every functional condition. Optimization results were compared with the limits values measured in homologation and with the acceptance limits values released by ENEL technical specifications for the MSD studied proving the effective methodology and the improvement obtained in terms of the safety of the system.

Keywords: Arcing time | DoE | Multibody model | MV electromechanical compartments | Parameterization

Abstract: The interest in developing customized external orthopaedic devices, thanks to the advent of Additive Manufacturing (AM), has grown in recent years. Greater attention was focused on upper limb casts, while applications to other body’s parts, such as the neck, were less investigated. In this paper the computer aided design (CAD) modelling, assessment and 3D printing with fused deposition modelling (FDM) of a customized neck orthosis are reported. The modelling, based on anatomic data of a volunteer subject, was aimed to obtain a lightweight, ventilated, hygienic and comfortable orthosis compared to the produced medical devices generally used for neck injuries. CAD models with different geometrical patterns, introduced for lightening and improving breathability, were considered, specifically, a honeycomb pattern and an elliptical holes pattern. These models were structurally assessed by means of finite elements analysis (FEA). Furthermore, an innovative composite material was considered for 3D printing. The material, Hemp Bio-Plastic® (HBP), composed by polylactic acid (PLA) and hemp shives, offers different advantages including lightweight, improved superficial finish and antibacterial properties. The results obtained in terms of design methodology and manufacturing by 3D printing of a prototype have shown the feasibility to develop customized cervical orthoses, with potentially improved performance with respect to cervical collars available on the market also thanks to the use of the innovative composite material.

Keywords: Additive Manufacturing | Bio-composite | CAD | Neck orthosis

Abstract: The special issue focuses on different features related to the design of additively manufactured lattice structures for biomedical applications. In many cases, the process-structure- property relationship and technical features are discussed from a morphological, mechanical, and functional point of view. In particular, an overview of the Additive Manufacturing processes, software methods, and design criteria, which allow the direct fabrication of 3D porous structures and lattices with tailored properties, are reported. Accordingly, the current special issue aims at providing new insights into the development of advanced devices and illustrates theoretical/experimental approaches used by researchers working in the field.

Abstract: The aim of this research is to develop patient-specific 3D mandible models, based on a limited number of measurements taken on the patient. Twenty Computed Tomography scans were used to build the respective 3D cad models of the mandible. Fifteen of these models were given as an input to a Principal Component Analysis software, and eight ‘principal’ mandible morphologies were produced. The following step was to identify the most efficient landmarks to ‘weight’ these morphologies when building a patient-specific model. Two further mandible computed tomography scans (a ‘normal’ mandible and a ‘severely resorbed’ one) were used to test the full procedure and to assess its accuracy. The accuracy of the 3D morphed surface resulted to range between 0.025 and 3.235 mm for the ‘normal’ mandible and between 0.012 and 1.149 mm for the ‘severely resorbed’ one having used eight landmarks to morph a ‘standard’ mandible. This work demonstrates how patient-specific models can be obtained registering the position of a limited number of points (on panoramic x-ray or on the physical model), reaching a good accuracy. This allows performing patient-specific planning and numerical simulations even for those cases where a computed tomography scan would not be available. In fact, this procedure can be interfaced with mesh morphing algorithms to automatically build finite element models. The accuracy of the procedure can be further improved, widening the mandibles computed tomography scans database and optimizing landmarks position.

Keywords: Morphing | Patient-specific models | Principal Component Analysis

Abstract: Performance characteristics of the products made of metallic materials such as wear resistance, fatigue strength, stability of gaps and strain between the connections, corrosion resistance, etc., depend to a large extent by the quality of their surfaces roughness. An interactive control of the manufacturing parameters which influence the surface roughness is particularly crucial in the construction of many mechanical components. The present paper devises a new method for statistical pattern recognition on samples produced by the process of robot laser hardening using network theory and describes its application to the determination of surface roughness. The method is based on the analysis of SEM images. Indeed the data characterizing the state of surface irregularities detected as extremely small segments contain indicators of surface roughness. Different methods of machine learning techniques designed to predict the surface roughness of robot laser hardened material are discussed.

Keywords: Machine interactive learning | Robot laser hardening | SEM images | Statistical pattern recognition | Surface roughness

Abstract: The concept of "surface modeling" generally describes the process of representing a physical or artificial surface by a geometric model, namely a mathematical expression. Among the existing techniques applied for the characterization of a surface, terrain modeling relates to the representation of the natural surface of the Earth. Cartographic terrain or relief models as threedimensional representations of a part of the Earth's surface convey an immediate and direct impression of a landscape and are much easier to understand than two-dimensional models. This paper addresses a major problem in complex surface modeling and evaluation consisting in the characterization of their topography and comparison among different textures, which can be relevant in different areas of research. A new algorithm is presented that allows calculating the fractal dimension of images of complex surfaces. The method is used to characterize different surfaces and compare their characteristics. The proposed new mathematical method computes the fractal dimension of the 3D space with the average space component of Hurst exponent H, while the estimated fractal dimension is used to evaluate, compare and characterize complex surfaces that are relevant in different areas of research. Various surfaces with both methods were analyzed and the results were compared. The study confirms that with known coordinates of a surface, it is possible to describe its complex structure. The estimated fractal dimension is proved to be an ideal tool for measuring the complexity of the various surfaces considered.

Keywords: Fractal dimension | Hurst exponent H | Image analysis | Space component | Surface

Abstract: The article describes a new bio-inspired method for the Advanced Treatment of Industrial Sludge with a Closed Cycle Drying Process. This process represents an innovative way of treating sludge and other shovelable residues deriving from sludge treatment with centrifuges and other industrial processes taking place in large installations, such as refineries, steel mills, chemical plants, glass processing installations, cosmetics manufacturing facilities, pharmaceutical plants. The process is under development within the research project TAFIPACC funded by Horizon 2020. In particular, the process allows retraining Industrial Sludge into construction materials using the new Closed Cycle Drying Process. The study deals with sludge produced by an industrial treatment plant/industrial discharges and civil waste water in the industrial area of Priolo Gargallo (SR) Esso-Erg-Enichem petrochemical plants and by the municipalities of Priolo Gargallo, and Melilli. The plants produce about 30 cubic meters of sludge per day, disposed of 50% in underground dumps and for the other 50% in hazardous and non hazardous waste recovery plants. The difficulty in the treatment is mainly due to the nature of these muds, as pasty and difficult to mix with additives (cement, limestone, H2O, granulometric mix). The presence of bad odours derives from light and heavy hydrocarbons, aromatics, and organic solvents (benzene, toluene, styrene, xylene, etc), causing some problems to operators and inhabitants living in the areas surrounding the plants.

Keywords: Bio-inspired | De-pollution | Process design | Recycling | Sludge treatment

Abstract: Visibility is a very important topic in computer graphics and especially in calculations of global illumination. Visibility determination, the process of deciding which surface can be seen from a certain point, has also problematic applications in biomedical engineering. The problem of visibility computation with mathematical tools can be presented as a visibility network. Instead of utilizing a 2D visibility network or graphs whose construction is well known, in this paper, a new method for the construction of 3D visibility graphs will be proposed. Drawing graphs as nodes connected by links in a 3D space is visually compelling but computationally difficult. Thus, the construction of 3D visibility graphs is highly complex and requires professional computers or supercomputers. A new method for optimizing the algorithm visibility network in a 3D space and a new method for quantifying the complexity of a network in DNA pattern recognition in biomedical engineering have been developed. Statistical methods have been used to calculate the topological properties of a visibility graph in pattern recognition. A new nhyper hybrid method is also used for combining an intelligent neural network system for DNA pattern recognition with the topological properties of visibility networks of a 3D space and for evaluating its prospective use in the prediction of cancer.

Abstract: Although the CAD parameters allow to update easily the geometrical model, the numerical models updating into Finite Elements (FE) software with different mesh result to be often heavy, due to the necessity both to create new mesh and to make usually time consuming and complex CAE calculations for updating the loading conditions. The aim of the present research is to devise a reliable methodology and at the same time to reduce computational burden in the shape optimization studies of mechanical components. In particular, an integrated Multibody (MB) and Mesh-Morphing (MM) approach was developed to perform shape optimization, in order to reduce maximum tensions. Using the RBF Morph ACT Extension plugin implemented in the commercial solver FEM ANSYS® Mechanical vers. 18.2 along with the commercial MB software MSC ADAMS® vers. 2017, shape optimizations can be obtained in a very short time, by acting directly at the mesh so updating node positions and mesh elements geometry without bringing different geometrical models of the component into the FE environment. To validate the methodology, a crankshaft for a high performance Internal Combustion Engine (I.C.E.) was chosen, as case study, to optimize the fillet zones between web and pin.

Keywords: Crankshaft | FEA | Fillet zones | Multibody | Stress analysis

Abstract: The working principle of a Phase Change Memory (PCM) cell exploits the repeated reversible transition between a crystalline and an amorphous phase of chalcogenide alloys typically Ge2Sb2Te5, that are characterized respectively by a high (SET) and a low (RESET) conductive state. The change in density between the two phases (6%) induces a very high compressive stress to the active amorphous region by the surrounding crystalline materials. Moreover, the physical iterative transformation between crystalline and amorphous phase transformation introduces a swelling and deswelling effect. This is one of the key failure mechanisms that are limiting the reliability of the final integration of the PCM system. Knowledge of the mechanical properties of the amorphous phase is then an important factor. Amorphous structure, i. e. its short-range order, depends on the adopted formation procedure. In this paper we analyze the mechanical characteristics of sputtered amorphous Ge2Sb2Te5 thin layers and the modification introduced by ion irradiation, a procedure adopted to simulate the amorphous state produced by melt quenching. Measurements of Young's Modulus and Hardness were performed using Ultra High-Nano Indentation on plane samples. The values of both quantities increase of about 10–20% in the 30 keV Ge+ irradiated samples. This trend is due to the reduction of homopolar wrong bonds (Ge–Ge and Te–Te) present in the as deposited film. Thermal spikes associated to the impinging ion cause a local atomic rearrangement that results in a structure similar to that of the crystalline phase. The investigation was extended to cantilevers of length in the range 10–200 μm, with a layer of 100 nm Ge2Sb2Te5 deposited on 280 nm thick SiN. The cantilever modal analysis and the out of plane deflection measurements were correlated using a Finite Element modeling, that makes use of the mechanical values measured by Ultra high Nano Indentation. After deposition the amorphous Ge2Sb2Te5 layer is subject to a compressive mechanical shrinkage, this internal stress is released after ion implantation.

Keywords: Cantilever | Nano-indentation | Phase change material

Abstract: Computational Fluid Dynamics (CFD), as early used in the design stage, helps engineers to come up with the optimum design of a sail in a reasonable timeframe. However, traditional CFD tools are approximate and need to be validated when it comes to predicting the dynamic behaviour of non-developable shape with high camber and massively detached flow around thin and flexible membranes. Some of these approximations are related to the implementation of the constitutive material characteristics and assumption of their isotropic properties, while the sail aerodynamic performance is strongly influenced by the arrangement of sail panels as well as the orientation of the fibres in the composite structure. The present paper offers a methodology that enhances the understanding of the influence of panel arrangement and fibre orientation on sail performance. Fluid-structure-interaction (FSI) in a symmetric spinnaker was studied through an integrated CFD-CSM (Computational Structural Mechanics) analysis. A suitable triangular membrane element formulation of sail was adopted and the constitutive characteristics (elasticity and damping) of the Nylon superkote 75 were implemented in CSM model after being experimentally measured. The aerodynamic performance of sail in terms of drive force and side force was evaluated using both Reynolds Averaged Navier Stokes Simulations (RANS) and Shear Stress Transport (SST) turbulence model with a finite volume approach. A comparison between different panel arrangements was carried out under altered downwind flow conditions of wind speed and wind angle. Digital photogrammetry was employed to create the 3D reconstruction of the sail's flying shape and validate the results obtained by aeroelastic analysis.

Keywords: CFD-CSM analysis | Flying shape photogrammetry acquisition | Sail panel arrangement | SST model | Triangular membrane elements

Abstract: This paper proposes a replicable methodology to enhance the accuracy of the photogrammetric reconstruction of large-scale objects based on the optimization of the procedures for Unmanned Aerial Vehicle (UAV) camera image acquisition. The relationships between the acquisition grid shapes, the acquisition grid geometric parameters (pitches, image rates, camera framing, flight heights), and the 3D photogrammetric surface reconstruction accuracy were studied. Ground Sampling Distance (GSD), the necessary number of photos to assure the desired overlapping, and the surface reconstruction accuracy were related to grid shapes, image rate, and camera framing at different flight heights. The established relationships allow to choose the best combination of grid shapes and acquisition grid geometric parameters to obtain the desired accuracy for the required GSD. This outcome was assessed by means of a case study related to the ancient arched brick Bridge of the Saracens in Adrano (Sicily, Italy). The reconstruction of the three-dimensional surfaces of this structure, obtained by the efficient Structure-From-Motion (SfM) algorithms of the commercial software Pix4Mapper, supported the study by validating it with experimental data. A comparison between the surface reconstruction with different acquisition grids at different flight heights and the measurements obtained with a 3D terrestrial laser and total station-theodolites allowed to evaluate the accuracy in terms of Euclidean distances.

Keywords: Accuracy | Acquisition grid optimization | Digital surfaces models | Ground sampling distance | Structure-from-motion algorithms

Abstract: Objective: To investigate the influence of implant design on the change in the natural frequency of bone-implant system during osseointegration by means of a modal 3D finite element analysis. Methods: Six implants were considered. Solid models were obtained by means of reverse engineering techniques. The mandibular bone geometry was built-up from a CT scan dataset through image segmentation. Each implant was virtually implanted in the mandibular bone. Two different models have been considered, differing in the free length of the mandibular branch (‘long branch’ and ‘short branch’) in order to simulate the variability of boundary conditions when performing vibrometric analyses. Modal analyses were carried out for each model, and the first three resonance frequencies were assessed with the respective vibration modes. Results: With reference to the ‘long branch’ model, the first three modes of vibration are whole bone vibration with minimum displacement of the implant relative to bone, with the exception of the initial condition (1% bone maturation) where the implant is not osseointegrated. By contrast, implant displacements become relevant in the ‘short branch’ model, unless osseointegration level is beyond 20%. The difference between resonance frequency at whole bone maturation and resonance frequency at 1% bone maturation remained lower than 6.5% for all modes, with the exception of the third mode of vibration in the ‘D’ implant where this difference reached 9.7%. With reference to the ‘short branch’ considering the first mode of vibration, 61–68% of the frequency increase was achieved at 10% osseointegration; 72–79% was achieved at 20%; 89–93% was achieved at 50% osseointegration. The pattern of the natural frequency versus the osseointegration level is similar among different modes of vibration. Significance: Resonance frequencies and their trends towards osseointegration level may differ between implant designs, and in different boundary conditions that are related to implant position inside the mandible; tapered implants are the most sensitive to bone maturation levels, small implants have very little sensitivity. Resonance frequencies are less sensitive to bone maturation level beyond 50%.

Keywords: Bone properties | CAD | Dental materials | Endosteal implants | Finite element analysis | Implant stability | Material properties | Osseointegration | Reverse engineering

Abstract: The optimization of loading protocols following dental implant insertion requires setting up patient-specific protocols, customized according to the actual implant osseointegration, measured through quantitative, objective methods. Various devices for the assessment of implant stability as an indirect measure of implant osseointegration have been developed. They are analyzed here, introducing the respective physical models, outlining major advantages and critical aspects, and reporting their clinical performance. A careful discussion of underlying hypotheses is finally reported, as is a suggestion for further development of instrumentation and signal analysis.

Keywords: Damping | Early loading | Functional loading | Implant stability | Modal analysis | Osseointegration | Resonance frequency | Reverse torque | Ultrasound

Abstract: Objective: To assess the influence of implant thread shape and inclination on the mechanical behaviour of bone-implant systems. The study assesses which factors influence the initial and full osseointegration stages. Methods: Point clouds of the original implant were created using a non-contact reverse engineering technique. A 3D tessellated surface was created using Geomagic Studio® software. From cross-section curves, generated by intersecting the tessellated model and cutting-planes, a 3D parametric CAD model was created using SolidWorks® 2017. By the permutation of three thread shapes (rectangular, 30° trapezoidal, 45° trapezoidal) and three thread inclinations (0°, 3° or 6°), nine geometric configurations were obtained. Two different osseointegration stages were analysed: the initial osseointegration and a full osseointegration. In total, 18 different FE models were analysed and two load conditions were applied to each model. The mechanical behaviour of the models was analysed by Finite Element (FE) Analysis using ANSYS® v. 17.0. Static linear analyses were also carried out. Results: ANOVA was used to assess the influence of each factor. Models with a rectangular thread and 6° inclination provided the best results and reduced displacement in the initial osseointegration stages up to 4.58%. This configuration also reduced equivalent VM stress peaks up to 54%. The same effect was confirmed for the full osseointegration stage, where 6° inclination reduced stress peaks by up to 62%. Significance: The FE analysis confirmed the beneficial effect of thread inclination, reducing the displacement in immediate post-operative conditions and equivalent VM stress peaks. Thread shape does not significantly influence the mechanical behaviour of bone-implant systems but contributes to reducing stress peaks in the trabecular bone in both the initial and full osseointegration stages.

Keywords: Bone properties | CAD | Dental materials | Endosteal implants | Finite element analysis | Material properties | Osseointegration | Plateau implants

Abstract: Assembled systems composed of flexible components are widely used in mechanics to dampen vibrations and store or dissipate energy. Often, the flexible components of these systems are assembled via non-linear sliding contacts and yielding constraints. Geometric non-linearity along with non-linearity of stiffness, damping and contact pressure between flexible components greatly complicate the dynamic characterization of these assemblies. Therefore, such assemblies are characterised almost exclusively by means of experimental testing. This research analyses how classic ASME and ISO tolerance standards can be used to guarantee and control the conformity of these assembled systems with their functional requirements limiting the number of experimental tests. In particular the dependence of the dynamic behaviour upon functional tolerances is studied for a mechanical tensioner in a chain drive timing system of an internal combustion engine (ICE). The semi empirical methodology is based on displacement measurements and modal analyses. A multibody model with few degrees of freedom (MBM-FDoF) is proposed as the first approximation to reproduce the variability of the dynamic behaviour of the tensioner considering variations in functional tolerances.

Keywords: ASME-ISO tolerance specification | Deformation energy | Multibody model | Reverse engineering | Tensioner

Abstract: The complexity of optimal design of the motorcycle tubular frame is due to the conflicting nature of various main design criteria, namely, reduction in the frame mass, increase in torsional stiffness, restriction of bending stiffness and minimization of maximum structural stress. Frame optimization is achieved when different kinds of decision parameters are involved: discrete (e.g. standardized tube diameters available on the market) and continuous (e.g. angles and fillets). Nowadays, optimal design of motorcycle tubular frames still appears to be the result of engineers’ creativity and experience, as well as of further suggestions by test drivers. In the design workflow of tubular motorcycle frames Topology Optimization (TO) technique it is not a well-established practice. Thus, this paper aims to discuss the applicability of Solid Isotropic Material with Penalization (SIMP) method with filtering as it is likely to perform an effective topology optimization of motorcycle tubular frames. After tubular frame 3d acquisition, effective design domain was defined and topology optimization of a multi-load case was implemented in a commercial software. The case study of the “DUCATI 600SS” frame, consisting of three different cross-section tubes in chrome-molybdenum alloy steel, where the motor performs the stiffening function, provides the results to support the methodology by validating it with experimental data.

Keywords: 3d acquisition | Cross-section tubes | Design method | Multibody numerical simulations | Tube bending and torsion

Abstract: This paper deals with additive manufacturing techniques for the creation of 3D fetal face models starting from routine 3D ultrasound data. In particular, two distinct themes are addressed. First, a method for processing and building 3D models based on the use of medical image processing techniques is proposed. Second, the preliminary results of a questionnaire distributed to future parents consider the use of these reconstructions both from an emotional and an affective point of view. In particular, the study focuses on the enhancement of the perception of maternity or paternity and the improvement in the relationship between parents and physicians in case of fetal malformations, in particular facial or cleft lip diseases.

Abstract: The use of polymer composites has been increasing over the years and nowadays the requirements for designing high performance and lightweight fabrics and laminates for sail manufacturing have become more stringent than ever. The present paper offers an effective methodology that enhances the understanding of the influence of fibres orientation and arrangement of panels on sail performance. Constitutive characteristics of the ten commonly used sail cloths are experimentally measured and their influence on sail dynamic performance is compared using an aerodynamic approach. As expected also in industry 4.0 the method allows to control the production process and final product optimization.

Keywords: Aerodynamic coefficient | Apparent wind angle (AWA) | Apparent Wind Speed (AWS) | CFD analysis | Digital photogrammetry | RE | Turbulence model

Abstract: Background Additive manufacturing technologies are being enthusiastically adopted by the orthopaedic community since they are providing new perspectives and new possibilities. First applications were finalised for educational purposes, pre-operative planning, and design of surgical guides; recent applications also encompass the production of implantable devices where 3D printing can bring substantial benefits such as customization, optimization, and manufacturing of very complex geometries. The conceptual smoothness of the whole process may lead to the idea that any medical practitioner can use a 3D printer and her/his imagination to design and produce novel products for personal or commercial use. Aims Outlining how the whole process presents more than one critical aspects, still demanding further research in order to allow a safe application of this technology for fully-custom design, in particular confining attention to orthopaedic/orthodontic prostheses defined as components responding mainly to a structural function. Methods Current knowledge of mechanical properties of additively manufactured components has been examined along with reasons why the behaviour of these components might differ from traditionally manufactured components. The structural information still missing for mechanical design is outlined. Results Mechanical properties of additively manufactured components are not completely known, and especially fatigue limit needs to be examined further. Conclusion At the present stage, with reference to load-bearing implants subjected to many loading cycles, the indication of custom-made additively manufactured medical devices should be restricted to the cases with no viable alternative.

Keywords: Additive manufacturing | Fast prototyping | Fatigue resistance | Orthodontic implants | Orthopaedic implants | Prostheses

Abstract: This work describes an integrated method of 3D modelling algorithms with a modal approach in a multibody environment which provides a slimmer and more efficient simulation of flexible component contacts realistically reproducing system impacts and vibrations. A non-linear numerical model of the impulse contact forces based on the continuity approach of Lankarani and Nikravesh is developed. The model developed can evaluate deformation energy taking into account the material's characteristics, surface geometries and the velocity variations of the bodies in contact. ADAMS®-type modelling is applied to the sliding contacts of the links of a chain and its mechanical tensioner (“blade”) in the timing of an internal combustion engine. The blade was discretized by subdividing it into smaller components inter-connected with corresponding centres of gravity through 3D General Forces. Static and dynamic tests were performed to evaluate the stiffness, damping and friction parameters for the multibody model and to validate the methodology.

Keywords: Flexible body | Friction forces | Hysteresis damping | Impact | Slip

Abstract: This work describes a simple, fast, and robust method for identifying, checking and managing the overlapping image keypoints for 3D reconstruction of large objects with numerous geometric singularities and multiple features at different lighting levels. In particular a precision 3D reconstruction of an extensive architecture captured by aerial digital photogrammetry using Unmanned Aerial Vehicles (UAV) is developed. The method was experimentally applied to survey and reconstruct the 'Saraceni' Bridge' at Adrano (Sicily), a valuable example of Roman architecture in brick of historical/cultural interest. The variety of features and different lighting levels required robust self-correlation techniques which would recognise features sometimes even smaller than a pixel in the digital images so as to automatically identify the keypoints necessary for image overlapping and 3D reconstruction. Feature Based Matching (FBM) was used for the low lighting areas like the intrados and the inner arch surfaces, and Area Based Matching (ABM) was used in conjunction to capture the sides and upper surfaces of the bridge. Applying SIFT (Scale Invariant Feature Transform) algorithm during capture helped find distinct features invariant to position, scale and rotation as well as robust for the affinity transformations (changes in scale, rotation, size and position) and lighting variations which are particularly effective in image overlapping. Errors were compared with surveys by total station theodolites, GPS and laser systems. The method can facilitate reconstruction of the most difficult to access parts like the arch intrados and the bridge cavities with high correlation indices.

Keywords: Architectural reconstruction | Area Based Matching | Feature Based Matching | Photogrammetry | SIFT algorithm

Abstract: This paper describes a methodology for carrying out an accurate mechanical characterization of an amorphous hyperelastic rubber-like material (carbon black filled natural rubber) by a custom-made experimental setup for bulge testing. Generally, during sample testing the slight anisotropy of the internal polymer structures, primarily due to the calendering process is neglected. This methodology is able to evaluate these effects. A hydraulic circuit inflates a thin disk of rubber blocked between two clamping flanges with adjustable flow rate, thus controlling the speed of deformation of the sample. The device has a sliding crossbar, which moves proportionally as the membrane inflates. A stereoscopic technique is able to capture with pixel precision and identify the strain on a silk-screen grid printed on the upper surface of the sample. For each acquisition step, the epipolar geometry of the image pairs is represented in a single absolute reference system integral to the experimental setup. The acquired images are processed using geometrical algorithms and different filters. In this way an extremely precise 3D reconstruction of the sample is created during the bulge test. Slight anisotropic behaviors due to the rubber calendering process have been observed and measured since the first steps of the bulge test, where the strains are minimal and principal strain direction in equibiaxial tension test are determined.

Keywords: Calendered rubber | Equibiaxial Bulge Test | Hyperelastic Materials | Stereoscopic Method | Transverse Isotropy

Abstract: Sail manufacture has undergone significant development due to sailing races like the America’s Cup and the Volvo around the World Race. These competitions require advanced technologies to help increase sail performance. Hull design is fundamentally important but the sails (the only propulsion instrument) play a key role in dynamic of sailboats. Under aerodynamic loads, sail cloth deforms, the aerodynamic interaction is modified and the pressure on the sails is variously distributed resulting in performance inconsistencies. The interaction between fluid and structure necessitates a solution which combines aerodynamic and structural numerical simulations. Furthermore, in numerical simulations the aeroelastic sail characteristics must be known accurately. In this paper, the dynamic performance of a Spinnaker was studied. Digital photogrammetry was used to acquire the images, make the 3D reconstruction of the sail and validate the models in Computational Fluid Dynamics (CFD) analysis. Orthotropic constitutive characteristics of ten different sail cloths were measured by experimental test. The methodology allowed to compare dynamic performance in terms of forces, pressure and vibration for the different sail cloths and different fiber orientations.

Keywords: CFD analysis | Detached eddy simulations | Pressure distributions | Sail aerodynamics | Turbulence models

Abstract: The shipment of heritage artefacts for restoration or temporary/travelling exhibition has been virtually lacking in customised packaging. Hitherto, packaging has been empirical and intuitive which has unnecessarily put the artefacts at risk. So, this research arises from the need to identify a way of designing and creating packaging for artefacts which takes into account structural criticalities to deal with deteriorating weather, special morphology, constituent materials and manufacturing techniques. The proposed methodology for semi-automatically designing packaging for heritage artefacts includes the integrated and interactive use of Reverse Engineering (RE), Finite Element Analysis (FEA) and Rapid Prototyping (RP). The methodology presented has been applied to create a customised packaging for a small C3rd BC bronze statue of Heracles (Museo Civico “F.L. Belgiorno” di Modica-Italy). This methodology has highlighted how the risk of damage to heritage artefacts can be reduced during shipping. Furthermore, this approach can identify each safety factor and the corresponding risk parameter to stipulate in the insurance policy.

Keywords: Cultural heritage | FEM | Laser scanning | Packaging | Rapid prototyping

Abstract: A methodology for integrating the CAD-CAE design of a chain drive system is presented by evaluating meshing angles. The methodology correlates the angles of engagement with transverse vibrations and the tensile force of the chain links, showing that the dynamic behaviour of a chain drive can be significantly improved by fine tuning the meshing angles. An objective parameter was introduced to evaluate divergence from correct meshing. Here the methodology is applied to optimize the timing chain system of a high power V12 quadruple overhead camshaft engine. The reliability of the method relies on multibody modelling all the components and accurate experimental tests. Correlating the experimental measurements provided exact modelling of the contact forces, exact evaluation of stiffness and damping values and precise dynamic modelling of the tensioners and guides. Finally, the dynamic performance of the two different primary stage chain drive layouts were compared.

Keywords: Chain stiffness | Contact force model | Meshing impact | Multibody dynamics | Tensioner | Transverse vibration

Abstract: The dynamics of a high-performance motorcycle are greatly influenced by the rider's weight and movements especially when the power-to-weight ratio is very high. Generally in motor vehicles, the driver's/rider's weight is a significant fraction of the entire system. This work is about ADAMS/View multibody modelling of a motorcycle and virtual rider who simulates handlebar interaction and saddle sliding. In the literature, the rider's influence is unrealistic being limited to considering him as a concentrated mass or in other cases as a fixed passive system. Even vehicle modelling is often inaccurate, referring at best to simplified models of rigid bodies. In this work, the vehicle and rider have been accurately modelled to most realistically reproduce the dynamic behaviour of the system. The motorcycle was modelled with 12 bodies incorporating concentrated flexibility for the two suspension units and considering the chassis as a flexible body using modal synthesis. The virtual rider is made up of 15 rigid bodies and has 28 degrees of freedom. To study the effects on the motorcycle of the rider's movements as well as the motorcycle's dynamics and performance, a monitoring system similar to that in the literature was used to read handlebar torque and engine and braking torque. Furthermore, in the literature there are simulations of standard manoeuvres whereas in this work an entire lap of Monza was simulated. There were simulations of a fixed and mobile rider validating the model in advance and thereafter monitoring the most significant dynamic parameters. The multibody model provides useful results at the design phase and insights into the whole vehicle/rider dynamic to setup all the reference parameters for immediately evaluating system effects.

Keywords: Multibody | Path tracking | Rider's effects | Rider-motorcycle system | Steering torque

Abstract: The aim of present work is the containment of the inertia forces, the stiffness components optimization and the fit tolerances of valve train in internal combustion engines (I.C.E.) 4T. The proposed methodology allows, through the development of a test machine, the evaluation of axial stiffness of tappet depending on eccentricity of the cam tappet contact, performing a functional analysis that simulate the behaviour of the system in operational condition, even if, some adjustment of tolerances of the fit between tappet and his guide, occurred. The dynamic study of the valve train, through modern computer codes, is performed by connecting lumped masses, springs and dampers that characterize each element. In numerical models the tappet is represented as constituted by the tappet and by the hydraulic element. Each of these elements is characterized by stiffness and mass. The structural rigidity of the tappet has, in fact, important effects on the dynamic behaviour of the entire valve train. The test machine makes possible the choice of the dimensional and geometrical tolerances of the fit between tappet and his guide; allows furthermore the evaluation of errors occurred during construction and integration phase. In addition, the test machine is also suitable for reverse engineering applications, makes it possible to automatically draw the cam profile in polar coordinates. © 2012 Springer Science+Business Media Dordrecht.

Keywords: Cam | Dynamics | Fit tolerance | I.C.E | Tappet | Timing system

Abstract: The valve return springs in the distribution chain of internal combustion engines constitute a fundamental component for the duration, efficiency and performance of the engine itself [1,2,3,4]. This is even more true for high-performance engines whose mechanical and thermal power leads to the premature deterioration of poorly designed components. The elevated forces in such engines necessitate, where the valve springs have not been substituted by alternative kinematic systems, progressive springs, i.e. springs with variable stiffness. Despite this fact, the literature does not contain any univocal methods for defining the geometry of this type of spring. In the present study, the question is approached on the basis of a numerical-iterative calculation, providing a general methodology which, starting from data regarding the functioning of the engine and the geometric volumes to be respected, leads to the definition of the optimal geometry of the helix, taking account of the trend of the stiffness, of the natural frequencies and of the loads over the entire operating range of the spring. Tests on springs calculated in this way were performed using multi-body software, in order to verify the correspondence between the initial design data and the real behaviour of the geometry generated. © 2011 SAE International.

Abstract: The valve return springs in the distribution chain of internal combustion engines constitute a fundamental component for the duration, efficiency and performance of the engine itself [1,2,3,4]. This is even more true for high-performance engines whose mechanical and thermal power leads to the premature deterioration of poorly designed components. The elevated forces in such engines necessitate, where the valve springs have not been substituted by alternative kinematic systems, progressive springs, i.e. springs with variable stiffness. Despite this fact, the literature does not contain any univocal methods for defining the geometry of this type of spring. In the present study, the question is approached on the basis of a numerical-iterative calculation, providing a general methodology which, starting from data regarding the functioning of the engine and the geometric volumes to be respected, leads to the definition of the optimal geometry of the helix, taking account of the trend of the stiffness, of the natural frequencies and of the loads over the entire operating range of the spring. Tests on springs calculated in this way were performed using multi-body software, in order to verify the correspondence between the initial design data and the real behaviour of the geometry generated. Copyright © 2011 SAE International.

Abstract: The performance of solid oxide fuel cells is affected by various polarization losses, usually grouped in Ohmic, activation, and concentration polarizations. Under typical operating conditions, these polarization losses are largely dependent on cell materials, electrode microstructures, and cell geometry: as an example, the performance of a tubular cell is strongly limited by the Ohmic polarization due to the long current path of electrons, while in a planar cell each of these losses has a comparable effect. It is therefore of interest, in the case of planar geometry, to investigate the main performance limiting factors. In this paper, a performance evaluation of planar circular-shaped sealless SOFC cells was performed. Two different designs of planar cells are considered. Both have a porous NiO-YSZ (yttria stabilized zirconia) anode as mechanical support, a NiO-YSZ anode active layer, and an YSZ electrolyte, and they only differ in the cathode design: (1) strontium doped lanthanum manganate (LSM)-YSZ cathode functional layer and LSM cathode current collector layer; (2) yttria doped ceria blocking layer and lanthanum strontium cobalt ferrite oxide (LSCF) functional layer. The characterization was performed by taking V-I measurements over a range of temperatures between 650°C and 840°C with hydrogen as fuel and air as oxidant. The experimental data analysis consisted in the analysis of some typical performance indicators (maximum power density (MPD); current density at 0.7 V). The dependence of the cell performance on the various polarization contributions was rationalized on the basis of an analytical model- through a parameter estimation of the experimental data-devoted to the determination of the main polarization losses. Based on the results of the investigation, it is concluded that LSCF cathodes are really effective in decreasing the cathode activation polarization, allowing the reduction in operating temperature. Copyright © 2009 by ASME.

Abstract: In the present study, the authors performed a dynamic analysis of the desmodromic timing system, where the valve lifter is realized by conjugate cams, using a methodology of modal synthesis to examine the effects of the deformability of the principal parts, and evaluating the deformations and vibrations of the components under various operating conditions. With this aim, a virtual 3D model and a multibody calculation program were used in a concentrated parameter model, requiring the choice of numerous parameters that greatly affect the results of the analysis. It was therefore important that, within the variability range of these parameters, the values adopted rendered the behavior of the analytical model as close as possible to that of the real system. Finally, the need to evaluate some of the more important aspects of the dynamic system (such as values of clearances, stiffnesses and damping at contacts, and stiffnesses and damping of shafts and belt) made it necessary to validate the model through comparison with experimental trials conducted to determine the valve motion and to measure the strain on the distribution belt.

Keywords: Desmodromic timing system | Dynamics | Flexible bodies | Modal synthesis

Abstract: In this study, a methodology based on co-simulation was developed for the multibody parametric modelling of a motorcycle with an anthropomorphic model of the rider. This co-simulation uses two different software programs, integrated to ensure a complete exchange of information between them in real time. The paper reports the effects induced by the movement of the rider's body on the dynamics and performance of a motorcycle. The legs of an anthropomorphic model were used as kinematics to control transverse movements of the motorcycle. The control system inputs are the geometric characteristics of the road (length, width and radius of curvature) and the speed of the vehicle along the track. For the dynamic behaviour of the motorcycle, the only channels currently operated by the control system are steering angle and engine torque, which are determined in accordance with the input parameters.

Keywords: Control | Dynamic | Motorcycle | Multibody | Rider

Abstract: The main purpose of the present study was to optimize a prototype hexapod robot, called Gregor I, through reverse engineering techniques. The robot is based on experimental observations of the cockroach with regard to mechanical design and the locomotion control strategy. This paper reports on the design phase of a hexapod robot, where the basic geometry of the system is defined through solid modeling and improved through kinematic and dynamic studies, using multi-body software. The dynamic simulation environment made it possible to study the performance of the system under different working conditions. Guidelines for an optimization process of the hexapod structure were drawn from these analyzes, aimed at the improvement of specific characteristics: speed, payload and climbing capabilities. Finally, the robot model and the robot prototype were compared.

Abstract: Defining a procedure for the characterization of the crankshaft and entire engine unit, based on CAD-FEM multi-body methodology, would provide an analysis tool which avoids the simplified hypotheses usually accepted when designing these components. The methodology is based on the Craig-Bampton method, i.e. on the theory of component mode synthesis. According to the Craig-Bampton theory, the deformation of a flexible crankshaft interfacing with the rest of the engine is obtained through static and normal modes, considering the discretized model with a large number of degrees of freedom and using modal truncation. It is based on the separation of interface and internal d.o.f. Using modal stress analysis has the advantage of reducing the d.o.f. of the FEA model. The multi-body model includes the elasticity of the camshaft and the reduced inertia of the gearbox and timing system. Comparing simulations performed at different engine speeds, the crankshaft evidenced the angular oscillations of generic sections of the axis and shaft, without separating the bending and torsional d.o.f. At higher engine speeds, the vibrational response showed how the harmonics with greater amplitude correspond to the crankshaft's first natural modes and are excited by some harmonics present in the engine moment.