Geometric modeling and processing

Nowadays, driving simulation devices represent a continuously evolving and developing area in the world of virtual reality. One of the fundamental elements in the design of driving software is the track model. This work aims to study the use of advanced technologies for the three-dimensional modeling of a racing track in a driving simulator. Specifically, it employs the LiDAR methodology to acquire the three-dimensional coordinates of a 1 km long circuit located on the Fisciano campus of the University of Salerno. The purpose of this work is to explain and present a novel track acquisition and modeling methodology within the realm of simulated driving reality. Following the study, the Virtual Reality Laboratory's driving simulator at the Department of Industrial Engineering conducted tests to validate the proposed circuit model. The test rides analyzed the realism of the driving experience, thereby validating the proposed track model. This phase was complemented by a series of proposals for possible future developments in the field of three-dimensional modeling applied to driving simulation and beyond. In the end, the 3D model obtained demonstrated the high definition of the acquired result and the speed with which multiple data were obtained simultaneously, thanks to the laser scanner used.

Keywords: 3D modeling , driving simulation , LiDAR data , real-world driving , track modeling , virtual environment , virtual reality , virtual reality

Designing customized orthodontic treatments presents a significant challenge due to the diverse and heterogeneous requirements that must be met to correct misaligned teeth and malocclusions. These requirements include specific directives from orthodontists, individual patient considerations, physiological constraints, and technological limitations. The current approach mainly involves collaboration between technicians and orthodontists utilizing specialized CAD software and implementing manual methodologies. This paper outlines the formalization of an algorithm developed to facilitate the design of these medical treatments. A mathematical model based on existing knowledge is proposed to automate the generation of a patient's final dental configuration, which serves as the foundation for producing all necessary devices for the treatment plan. The mathematical model has been validated through collaboration with orthodontists and a manufacturer specialized in orthodontic devices.

Keywords: Design method , Knowledge formalization , Orthodontic treatment , Product customization

Unlike rigid mechanisms, compliant mechanisms offer frictionless motion with enhanced precision in compact designs by deriving their motion from the deflection of flexible elements. The Tetra joint, a class of compliant spherical joints, has garnered significant attention in recent years. However, its unique design-featuring a trapezoidal cross-section and trapezoidal blade flexures-poses significant modeling challenges. This work extends our previous study, where we developed a geometric model for streamlined Tetra joint modeling suitable for implementation in Computer-Aided Engineering (CAE) platforms. In this study, we expand the applicability of this model to the analysis and simulation of complex robotic systems, specifically compliant Delta robots. A compliant Delta robot constructed with Tetra joints, termed DeltaFlex, is numerically and parametrically modeled using the developed geometric model of the Tetra joint. To identify the primary contributors to kinematic errors, a systematic analysis is performed. This methodology combines numerical simulations with statistical correlation analysis to evaluate the relationships between design parameters and system errors. The results reveal that the angle between the two sides of the triangle in the Tetra joint has a dominant effect on system errors.

Keywords: CAE , Compliant mechanism , DeltaFlex robot , FEA , Parallel robots , Parametric modeling , Tetra joint

Additive manufacturing represents one of the most significant improvements in Industry 4.0. Design for additive manufacturing is the discipline that studies integrated CAD/CAE tools with guidelines for optimizing 3D printing in terms of cost, process time, quality, and precision. In this context, machine learning is used to support control and decision-making activities in additive manufacturing. However, the use of machine learning methods is generally limited to one single process phase. No studies are proposing a machine learning approach focused on different phases of the product lifecycle, from the early design phase to manufactured parts. In the literature, machine learning applications for additive manufacturing regard only one specific phase of the production process. This paper describes current improvements in the integration of additive manufacturing and machine learning, highlighting limitations, and proposes to include different phases of the product lifecycle while designing with machine learning tools. The research provides a guide to develop a new design platform where machine learning supports the engineers in the definition of the product design and process parameters.

Keywords: Design for additive manufacturing , Laser-powder bed fusion , Machine learning , Product lifecycle

Regenerative medicine is an emerging discipline that investigates the possibilities of restoring portions of damaged biological tissues in a controlled way. An interesting practice in this field consists in the implantation of biomimetic scaffolds colonized by mesenchymal stem cells taken from the patient. In this work, a set of design guidelines for customized biomimetic scaffolds was analyzed, and a full procedure aimed at implementing them for the treatment of a real clinical case was outlined. In detail, a highly sustainable and biocompatible material obtained from chemical processing of fish industry by-products was selected. The primary phases of the proposed design procedure consisted in biomedical data acquisition, parametric modelling of the damaged region to regenerate, structural design of the scaffold based on the avoidance of stress shielding effects, and evaluation of the physiological pressure to apply on the implanted porous construct to maximize mature bone formation.

Keywords: CAD Modelling , Mechanical Design , Tissue Engineering

The development of additive manufacturing has made these technologies suitable for fabricating end products. This encourages companies to identify quickly parts in large databases for which switching from traditional manufacturing technologies to additive manufacturing is convenient. Typically, the manufacturing process selection is made by experts who weigh various parameters, but evidence suggests that intelligent systems could beneficially replace or aid this manual selection. One challenge in using manufacturing data for advanced analysis and machine learning is that it is usually unlabeled, and manual data labelling is expensive and time-consuming. This paper deals with the application of an enhanced unsupervised learning algorithm that automatically identifies parts suitable for additive manufacturing based on parts geometry as a preliminary step of process selection. One hundred randomly selected parts were evaluated by manufacturing experts through a survey and then clustered by the proposed algorithm. The comparison of the manual and algorithmic classifications, using unsupervised learning, regarding suitability for additive or traditional manufacturing is the main original contribution of this study. Overall, 78% convergence between most experts' designations and the unsupervised learning algorithm is achieved. For those parts where expert opinions are substantially aligned, the algorithm showed a 90% convergence rate with human choices.

Keywords: Additive manufacturing , Computer-aided design , Hierarchical clustering , Image processing , Machine learning , Unsupervised learning

In bone tumor resection surgery, patient-specific cutting guides aid the surgeon in the resection of a precise part of the bone. Despite the use of automation methodologies in surgical guide modeling, to date, the placement of cutting planes is a manual task. This work presents an algorithm for the automatic positioning of cutting planes to reduce healthy bone resected and thus improve post-operative outcomes. The algorithm uses particle swarm optimization to search for the optimal positioning of points defining a cutting surface composed of planes parallel to a surgical approach direction. The quality of a cutting surface is evaluated by an objective function that considers two key variables: the volumes of healthy bone resected and tumor removed. The algorithm was tested on three tumor cases in long bone epiphyses (two tibial, one humeral) with varying plane numbers. Optimal optimization parameters were determined, with varying parameters through iterations providing lower mean and standard deviation of the objective function. Initializing particle swarm optimization with a plausible cutting surface configuration further improved stability and minimized healthy bone resection. Future work is required to reach 3D optimization of the planes positioning, further improving the solution.

Keywords: Computer-aided surgery , Optimization , Orthopedic surgery , Surgical planning , Tumor resection

In the field of structural engineering, the optimization process is crucial for ensuring both the efficiency and safety of designed structures. The persistent search for solutions that maximize structural performance while minimizing costs presents a fascinating and complex challenge. In this context, this paper aims to analyze and compare three different Nature-inspired optimization algorithms that are derived from theory of biological evolution, swarm intelligence, and chemical and physical processes. Specifically, the study aims to provide a comprehensive overview of the performance and characteristics of Genetic Algorithms, the Firefly Algorithm, and the Group Search Optimizer Algorithm in the context of structural optimization within the ANSYS APDL environment.

Keywords: ANSYS , finite element method , meta-heuristic algorithms , Structural optimization

Tread geometry is one of the parameters that influence wear. Hence, investigating tread geometries and their evolution during tire usage becomes crucial for mitigating wear-related emissions. Among the state-of-the-art measurement methods, 3D scanning is notable for its ability to provide detailed insights into tread geometry. This study introduces a methodology for analysing the evolution of tire tread geometry, aiming to improve tire wear analysis. The proposed approach based on first derivative analysis and discrete data binning, was tested exploiting a benchmark tire generated virtually in a CAD software and sampling a point cloud on its surface, resembling 3D scanning acquisition. The results show its capability of leveraging 3D scanning technology to provide detailed insights into tread geometry by isolating sampled points located within grooves from those belonging to the outermost surface. The recognition of geometric features allows for the separate analysis of the different layers, extending the capability of average profile-based wear assessments to complex tread patterns, such as directional tires.

Keywords: Tire 3D scanning , Tire wear , Tread geometry evolution

Additive manufacturing components are prone to defects, including warping and cracking, which can significantly impact their mechanical performance. Determining deformations in lattice structures remains challenging. This paper presents a methodological framework for computing deformation matrices in additively manufactured lattice samples using 3D scanning. The sample's geometry is acquired through 3D scanning, registered to a reference model, and vertices are determined and used for computing deformation metrics, including volumetric scaling factors, isovolumetric scaling, and angular deformations. A sensitivity analysis comparing four association criteria demonstrates the reliability of the Gaussian Best Fit Plane External. Assessing deformation in lattice structures can be useful for optimizing printing parameters and compensating for process-induced deformations.

Keywords: 3D scanners , Additive Manufacturing , Deformations , Lattice Structures

The availability of foaming materials with properties that vary according to the heat transferred to the filament in the fused filament fabrication (FFF) process provides the opportunity to develop new design methodologies that allow the exploitation of the range of characteristics offered by these materials. In this work, an integrated CAD-CAM method to realize graded density foamed components via FFF is proposed. The method consists in the post-processing of a G-code file obtained from a CAD model according to functional requirements defined by a density map volumetric model. The method relies on the material property-process parameters correlation to drive the foaming in a specific extruder configuration. The temperature effect on extrusion width and density is experimentally investigated as the primary process parameter driving the foaming behaviour of a commercially available filament. Based on the density map of the volumetric model and the experimental characterization, temperature and extrusion amount are updated in the G-code file.

Keywords: Additive Manufacturing , Design Method , Foaming , Functionally Graded Density , Fused Filament Fabrication , Polylactic Acid

The shape and tuning of bells provide helpful information about where the instrument was manufactured or located and the casting and tuning processes used. For this purpose, both shapes catalogues and methodologies for physical modelling and simulations of musical instruments' dynamical behaviour are presented in the literature. In several areas of the world, medieval or Renaissance bells are rare because of the remelting of the vast majority of specimens following fractures or breaks caused by wear and tear or traumatic events, such as earthquakes. As a result, the original geometric shape can only be reconstructed by analysing the relevant melting pots excavated by archaeological campaigns. Traditionally, such an analysis is carried out manually by archaeologists. The results are blurred by the difficulty in determining the axis of symmetry and the profiles of small fragments; furthermore, the fragments can rarely be reassembled on the fracture surfaces. To address these drawbacks, this research suggests a computer-based method for virtually reconstructing the bell shape from mantle fragments.

Keywords: 3D archeology , Automatic feature recognition , Cultural heritage , Medieval Bells

Design review is a tool used to identify errors in products before their physical prototype is realized. Currently, 2-dimensional (2D) Computer Aided Design (CAD) digital or paper drawings are used to conduct design review. There is the risk that users who are not practical with CAD software may be excluded from this process. In addition, the dimensions and scales of CAD models may be lost due to the complexity of displaying them on a PC screen. VR technologies overcome these limitations. The idea of “Virtual Design Review” (VDR) allows users to live an immersive experience and see, manipulate, test, examine, and identify errors of virtual products in real-time, realistically and in total safety already in the early design stages, without undertaking the time and costs of building them. The objective of this work is to propose a proper workflow for conducting VDR sessions on complex assemblies, whose design process is developed over a Product Lifecycle Management (PLM) platform like 3D Experience. VR modules offered by this platform to execute VDRs are explored and tested.

Keywords: 3D Experience platform , Cloud-Based Design and Manufacturing , Fusion Engineering , PLM , Virtual Design Review and Digital Twin

Virtual reality (VR) technologies have shown significant potential in enhancing the automotive design process by providing immersive, interactive, and collaborative environments for reviewing complex vehicle architectures. Traditional CAD models and physical prototypes often struggle to offer the flexibility needed for rapid iteration and spatial understanding, especially for systems such as hydrogen-powered commercial vehicles. This study aims to develop a VR platform to improve the collaborative review of the internal architecture of a hydrogen-powered commercial vehicle, specifically focusing on the spatial arrangement and interaction of critical components such as hydrogen tanks, fuel cells, and batteries. The goal is to enhance design processes, reduce iteration costs, and improve spatial understanding and decision-making within automotive teams. The VR environment was built using Unity 3D and optimized for mobile VR platforms, incorporating features such as interactive component manipulation, dual locomotion modes (teleportation and free movement), and real-time collaboration. The platform was tested with a range of users, including automotive professionals and students, to evaluate its usability, performance, and impact on spatial understanding and user engagement. User feedback demonstrated high levels of satisfaction, with 85% of participants reporting improved spatial understanding, 80% preferring VR over traditional CAD tools, and 90% noting increased engagement. The VR platform enabled faster completion of assembly tasks (40% faster than traditional methods) and improved collaborative decision-making. However, challenges such as system performance issues, motion sickness, and a steep learning curve were reported by some users, particularly nontechnical users. The VR platform developed in this study significantly advanced the collaborative and immersive review of automotive designs, offering tangible benefits in terms of engagement, spatial comprehension, and design iteration efficiency. While there were limitations related to hardware requirements and user accessibility, the results highlight the transformative potential of VR in automotive design and education.

In orthopedic surgery, bone tissues aid in the reconstruction of damaged or missing bone and ligaments, allowing patients to achieve optimal motor function recovery. A musculoskeletal tissue bank collects and certifies donated tissue for transplantation. However, sometimes suitable bone tissue is unavailable or incompatible geometrically with the required implant. Custom-made, biocompatible artificial bone tissue development could mitigate such challenges. Scaffolds, either biological or synthetic, promote bone regeneration within the body. Despite research on their chemical compositions and mechanical properties, limited attention is given to their geometric design and personalized shape. This study presents a method for designing bone scaffold geometry using additive manufacturing in a biocompatible material. The aim is to create a scaffold with variable density, from denser cortical to less dense medullary zones. CT images determine bone tissue density, compared to the density imposed on the scaffold. Additionally, the printability of the PEEK, the chosen material, is investigated.

Keywords: 3D Printing , Biomaterials , CAD , Lattice structures , PEEK

Extended Reality (XR) refers to technologies that allow linking virtual and real worlds and include, in a broad sense, Virtual (VR), Augmented (AR), or Mixed (MR) Reality. The interest in XR is increasing mainly in training operations; however, it is important to consider that XR techniques could sacrifice realism and could require high costs to reproduce real environments. The present study addresses this problem and aims to experimentally test how the level of realism can be implemented and increased in practice and how different levels of realism impact the user experience. A framework for the reconstruction of 3D scenes using photogrammetry is proposed and an experimental campaign is presented to understand the user experience of an XR application, with particular attention given to participants' feedback about the level of realism of the virtual scenario. The focus of the research is to outline the improvement of the virtual experience owed to the photogrammetric reconstruction. Participants were asked to give their opinions on the comparison between the reconstructed 3D environment and a conventional shaded virtual environment made up of 3D CAD models. This paper contributes to the still limited empirical debate about the implementation of different levels of realism in virtual applications and its impact on participants' experience. Results show that participants appreciated the photogrammetric reconstructed realistic scenario, proving that realistic scenes can improve the user experience.

Keywords: 3D modeling , experimental campaign , photogrammetry , questionnaire , realism , user experience , virtual reality

The increasing demand for lightweight automotive frames is pushing toward adopting composite materials and automating the related manufacturing and assembly processes. Carbon Fiber Sheet Molding Compounds, CF-SMC, enable custom-shaped car body parts fabrication through a single-step compression molding process. Nevertheless, conventional manual stack-up impacts productivity since it is the operation required to enable the compression molding. Robotic manipulation of the pre-shaped uncured composite stacks can relax the continuity between these two phases. The handling process requires dedicated grippers to keep the deformable composite stacks within the shape deviations required to fit on the compression mold. To this aim, a two-stage integrated approach to design the robotic grippers is presented in this work. Bounded by the maximum allowed deformation to fit the mold, the first stage returns the grasping pattern, that is the optimal grasp point map. The second stage aims to identify the lightest stiffer frame for the gripper. A Computer-Aided Design platform is adopted to integrate the two phases of the method.

Keywords: CAD Platform , CS-SMC , Integrated design , Robotic Grippers

Casting simulations evaluate the physics in the cavities, up to micro-physics in the formation of porosities, metallurgical structures and mechanical properties. As a limit in this procedure, a 3D CAD model of the mould is required, which is very time consuming to deliver. Therefore, the simulations can be little exploited in the initial conceptual phase and the equipment layout must be defined mainly based on the experience of practitioners. This research studies a Casting Simulation Assistant tool for Gravity Die Casting and Low Pressure Die Casting in order to calculate the simulation parameters and to deliver the simulation results as fast as possible. The paper discusses the necessary simplifications, the input and output data, the modelling technique, the software structure and the user interface. In particular, a mould is modelled as a thermal machine, with in- and out-flows of matter and energy. The tool is evaluated against the results from a commercial software, first on theoretical cases and then also on four real moulds. The Casting Simulation Assistant calculates the performance of the mould in a few seconds, allowing design parameters to be modified and recalculated interactively. The results can be used for the evaluation of the main performance of the mould as feasibility analysis, for production costs estimation, for the rapid comparison of different design variants in the conceptual design phase and to give a first assessment of a set of parameters in order to save time in the following simulations.

Keywords: Conceptual design , Gravity die casting , Low pressure die casting , Simulation assistant

Background: Mandibular reconstruction has evolved significantly since its inception in the early 1900s. Currently, the fibula free flap (FFF) is considered the gold standard for mandibular and maxillary reconstructions, particularly for extensive defects, and the introduction of Extended Reality (XR) and virtual surgical planning (VSP) is revolutionizing maxillofacial surgery. Methods: This study focuses on evaluating the accuracy of using in-house cutting guides for mandibular reconstruction with FFF supported by virtual surgical planning (VSP). Planned and intraoperative osteotomies obtained from postoperative CT scans were compared in 17 patients who met the inclusion criteria. The proposed analysis included measurements of deviation angles, thickness at the centre of gravity, and the maximum thickness of the deviation volume. Additionally, a mandibular resection coding including 12 configurations was defined to classify and analyze the precision of mandibular osteotomies and investigate systematic errors. Preoperative, planned, and postoperative models have been inserted in an interactive VR environment, VieweR, to enhance surgical planning and outcome analysis. Results: The results proved the efficiency of adopting customized cutting guides and highlighted the critical role of advanced technologies such as CAD/CAM and VR in modern maxillofacial surgery. A novel coding system including 12 possible configurations was developed to classify and analyze the precision of mandibular osteotomies. This system considers (1) the position of the cutting blade relative to the cutting plane of the mandibular guide; (2) the position of the intersection axis between the planned and intraoperative osteotomy relative to the mandible; (3) the direction of rotation of the intraoperative osteotomy plane around the intersection axis from the upper view of the model. Conclusions: This study demonstrates the accuracy and reliability of in-house cutting guides for mandibular reconstruction using fibula free flaps (FFF) supported by virtual surgical planning (VSP). The comparison between planned and intraoperative osteotomies confirmed the precision of this approach, with minimal deviations observed.

Keywords: fibula free flap , maxillofacial surgery , virtual reality , virtual surgical planning , VR , VSP

The engineering process is a critical area in the design and development of devices for scientific, industrial and technological applications. This process involves the conceptualization, design, prototyping and production of equipment suitable for specific operations or functions. The main objectives of equipment engineering are to optimize the performance, efficiency of functionality, safety and reliability of devices, as well as to reduce costs and production time. The application of advanced engineering methodologies, such as Computer-Aided Design (CAD), systems analysis and advanced manufacturing techniques such as Additive Manufacturing (AM), allows the creation of high specialized and high performance equipment to satisfy the specific needs of modern industries. In the framework of advanced technologies such as nuclear fusion, equipment engineering plays a key role in solving complex challenges and developing innovative solutions involving various aspects of engineering knowledge.

Keywords: Additive Manufacturing , CAD , Design Methods , Engineering Design , Prototyping