Abstract: Purpose: Reverse Shoulder Arthroplasty (RSA) is widely used to treat shoulder joint pathologies. However, this procedure may result in reduced range of motion (ROM), scapular notching, and prosthetic instability. These complications vary among patients, highlighting the need for individualized preoperative planning. This study introduces a novel parametric methodology to determine optimal glenoid component positioning by evaluating ROM, instability ratio, and the percentage of bone resected. Method: The proposed approach was applied to four patient models treated with two prosthetic designs. The methodology consists of four steps within a patient-specific parametric tool: 3D anatomical reconstruction, virtual surgical planning, biomechanical and geometric evaluation, and identification of optimal configurations. Fifteen glenoid component orientations were generated by varying tilt angles. The best configurations were identified based on ROM and instability assessments, while bone resection volume was calculated as an additional parameter. Results: Maximum values of abduction–adduction, internal rotation, and external rotation were 87.23°, 90°, and 70.59°, respectively, although not achieved in a single configuration. Instability ratios ranged from 0.23 to 0.62. Bone resection varied between 0.4% and 5.5%, depending on the configuration. Conclusions: This methodology provides a patient-specific framework to support preoperative planning in RSA.

Keywords: CAD-based planning | Glenoid positioning | Joint stability | Patient-specific modeling | Range of motion | Reverse shoulder arthroplasty

Abstract: This paper aims to evaluate whether augmented reality (AR) visualisations can improve engineering students’ learning experience. Three AR applications were developed and then integrated into classroom exercises in a Computer-Aided Design (CAD) course. The students used applications on their smartphones, through which they manipulated AR parts’ models, visualised components’ main views and assemblies’ compositions. Subsequently, students completed a dedicated questionnaire, composed of five sections. Results showed that students prefer innovative visualisation over the traditional one, improving their understanding of complex geometries, views and assemblies. Furthermore, the findings revealed that prior familiarity with AR and VR tools did not significantly influence perceptions. The applications’ usability, assessed through the System Usability Scale (SUS), was acceptable, while the Short User Experience Questionnaire (UEQ-S) average scores were highly satisfactory.

Keywords: Augmented Reality | Engineering Education | Innovative Education

Abstract: Ankle injuries are common due to the joint’s role in weight-bearing and dynamic motion. Finite element method (FEM) has become a valuable tool for understanding joint biomechanics and planning clinical interventions. However, many existing models are limited by static simulations, simplified geometry, or generalised approaches that do not focus specifically on the talus-tibial joint. This study presents a subject-specific FEM framework of the ankle, integrating magnetic resonance imaging (MRI) and gait data from a healthy 49-year-old male. The tibia and talus were reconstructed from MRI and cartilages were modeled using a custom method to compensate for limitations in image resolution. Kinematic data was collected using the Xsens motion capture system and applied to a dynamic FEM developed in Abaqus. The model yielded contact pressures between 1.2 and 21.8 MPa and maximum von Mises stresses up to 5.7 MPa. The stress distribution was predominantly lateral, consistent with known biomechanical patterns. This framework allows realistic simulation of ankle mechanics and provides a basis for assessment of pathological conditions and surgical planning.

Keywords: 3D Modeling | Ankle | Finite Element Analysis | Gait Analysis

Abstract: In response to the growing need for adaptive optimization algorithms capable of handling complex, multimodal, and high-dimensional search spaces, this paper introduces the Structured Random Cycle-guided Algorithm (SRCA). SRCA is not presented as a fundamentally new optimization paradigm, but rather as an architectural synthesis and a unified adaptive framework for dynamic operator selection. Based on a cycle-structured architecture, directional and stochastic search behaviors are dynamically selected at the individual level. The algorithm orchestrates well-established structured movements with a diverse pool of stochastic exploration strategies, enabling a coherent and adaptive balance between exploration and exploitation throughout the optimization process. Unlike traditional metaheuristics that rely on fixed behavioral roles or static movement schemes, SRCA allows each individual to adapt its search strategy based on real-time population feedback, monitored through convergence and dispersion indicators. The performance of SRCA is quantitatively assessed under strictly identical experimental conditions on a comprehensive set of 23 benchmark functions, including multimodal and high-dimensional problems, as well as on six classical constrained engineering design problems. Numerical results demonstrate competitive convergence reliability and robustness across diverse optimization tasks, confirming the effectiveness of the proposed adaptive cycle-based framework.

Keywords: benchmark functions | constrained optimization | Metaheuristic algorithms | optimization | structured random cycle-guided algorithm

Abstract: The increasing use of geopolymers in the construction industry, driven by the need for eco-friendly production processes and the gradual replacement of Portland cement in such applications, leads to new scientific challenges. In particular, the availability of reliable tools to predict the mechanical response of this class of materials is becoming increasingly crucial for their application in a wider range of engineering solutions. In the context of this research work, and as a contribution to addressing these needs, a modeling framework based on a morphologically informed Representative Volume Element was developed and proposed. To this end, an X-ray tomographic technique was employed on geopolymer samples, and internal defects were quantified through morphometric image analysis. The resulting data were subsequently integrated into a Finite Element Method (FEM) code to build a Representative Volume Element incorporating a distribution of equivalent porosity. Therefore, numerical simulations were carried out using an explicit FEM code to reproduce a compressive mechanical test, and the results were compared with experimental data. Good agreement was observed between the experimental and numerical results, both in the linear elastic regime and during the damage initiation and failure phases of the specimens.

Keywords: CT scan | FEM | Geopolymers | morphometry | Representative Volume Element

Abstract: This work presents an experimental and numerical assessment of the hydrodynamic performance of the Olympic iQFOiL windsurfing class. Full-scale towing-tank tests were carried out at velocities between 3.0 and 7.0 m/s and at angles of attack from −1° to 4°, providing benchmark measurements of lift and drag forces. Preliminary Computational Fluid Dynamics (CFD) analyses revealed that Fluid Structure Interaction (FSI) effects needed to be included to achieve accurate predictions and good agreement with the experimental data. Numerical simulations were therefore performed over the velocity range 1–7 m/s at zero angle of attack. A parametric Computer Aided Design (CAD) model was developed to generate both the undeformed geometry and the deformed configurations obtained through Finite Element Method (FEM) structural analyses. The numerical campaign enabled a detailed investigation of pressure distributions and structural deflections, indicating negligible deformation up to 4 m/s. At higher velocities, neglecting hydroelasticity resulted in a noticeable underestimation of lift. The analysis of the velocity and pressure fields for the undeformed and deformed shapes provided an enhanced understanding of the behaviour of the iQFOiL, particularly in terms of the effective trim angle and the relative variation in the longitudinal position of the centre of pressure.

Keywords: Experimental testing | Fluid-structure interaction | iQFOiL | Numerical simulation | Windsurfing

Abstract: The present paper concerns the study of the influence of some geometrical parameters, in particular the depth-to-height ratio, and some mechanical properties, in particular Young’s modulus and Poisson’s ratio, on the response of homogeneous isotropic specimens subjected to the Brazilian splitting test. For this purpose, principal stresses and strains are evaluated at the specimen barycenter through finite element analyses carried out in the ANSYS environment. The relevant analyses are performed by adopting systematic variations in both geometrical and mechanical parameters within suitably defined ranges. The obtained numerical results are compared with commonly adopted reference stresses from the literature, showing that the plane stress assumption is independent of material properties for low depth-to-height ratios, and it is generally not realistic under standard testing conditions. Furthermore, the obtained results prove that the tensile principal stress typically assumed in the literature overestimates the actual value. Moreover, the strain field analysis indicates that the validity of the plane strain hypothesis depends jointly on the geometrical and mechanical characteristics of the specimen. Finally, the study proposes a graphical approach for the estimation of the actual tensile principal stress starting from conventional literature-based values, accounting for specimen-specific parameters. Future work will include the numerical validation of the behavior of the principal stresses along the specimen axis, as well as the experimental validation of the numerical results on a specimen basis, for instance, by employing full-field, contactless displacement measurement techniques.

Keywords: Brazilian splitting test | FEM model | homogeneous isotropic material | numerical simulations | strain analysis | stress analysis

Abstract: Accurate evaluation of the cerebral aneurysm rupture risk is currently a challenge. Indeed, an accurate prediction is crucial for optimising clinical surveillance and treatment decisions. This study aims to evaluate rupture risk by analysing hemodynamic and morphological factors that would influence aneurysm growth and rupture. A computational fluid dynamics approach was employed to simulate blood flow dynamics with aneurysm geometry obtained through angiography. The blood was modelled as a non-Newtonian, incompressible, turbulent fluid, using velocity profiles derived from transcranial Doppler ultrasound as the inflow condition. The outcomes of this investigation yield significant insights into the interior of the aneurysm, specifically regarding pressure distributions and wall shear stress. These were evaluated in conjunction with the characteristics of the aneurysm shape.

Keywords: Cerebral aneurysm | CFD | rupture

Abstract: 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

Abstract: The increasing interest in foiling sailing yachts, recently driven by the American’s Cup, led to a wider application even in small boats such as dinghies or windsurfing. Foiling seems to be recent but since the early twenty-century years, hydrofoils has been experimented in Italy. This paper shows the complete foil design process starting from classical wing design based on theoretical consideration and illustrating the importance of modern simulation environments in design processes. Commercial CFD code Ansys Fluent® has been used and the results have been compared with those obtained through ad hoc developed vortice lattex method software, showing a substantial agreement with RANS simulation and theoretical calculation in front of incredible time reduction for simulation process that would allow a numerical planform optimization in a reasonable time.

Keywords: CFD | Foiling | Yacht design

Abstract: In the Medical Reverse Engineering (MRE) field, the manipulation of computed tomography (CT) scans from patients is complex, especially regarding the development of 3D anatomical models of patients’ anatomy. This complexity depends on the variability of human anatomy, thus involving several challenges in the fabrication of custom biomedical devices. Low back pain is a worldwide widespread disease, whose cause is still unknown today. Indeed, a comprehensive understanding of spinal biomechanics is the goal that needs to be achieved for the evolution of surgical therapies and the design of useful devices for pathologies. Hence, Finite Element (FE) modelling of the lumbar spine is an important tool, useful for understanding the spinal physiological and pathological conditions. However, the obstacle of complex geometries is of extreme relevance. The aim of this paper is to support the existing literature to provide new models that can be used in FE modelling of the spine. Therefore, a novel model of the lumbar spine L4-5 with simplified intervertebral disc geometry was created and then the following model was validated using experimental data obtained from the literature about the long-term loading.

Keywords: Biomechanics | Intervertebral disc | Lumbar spine | Medical Reverse Engineering

Abstract: The use of osseointegrated implants as a solution for amputation treatment, providing a stable connection between the stump and prosthetic limb, is expanding its application to different anatomical districts. A particular focus is put on upper limb amputations, where socket-suspended systems often lead to high abandonment rates of prostheses and osseointegrated implants can enhance prosthetic-limb use, and improve bone perception and range of motion, leading to a better quality of life. This study aims to evaluate the effect of bone-implant interference and implant length of a straight implant, on the primary stability of a humerus CAD model through finite element analysis. The results suggest that a compromise can be made between interference and length to accommodate varying bone morphology and stump length. Additionally, the study results may suggest re-evaluating the prescribed weight limits for transhumeral implants based on their actual load-bearing capacity.

Keywords: <h3 class="h4">Author keywords</h3> | finite element method | osseointegration | primary stability

Abstract: Total ankle arthroplasty (TAA) is a common surgical intervention for end-stage ankle arthritis. This study investigates the impact of polyethylene insert size on TAA stability. Dynamic finite element modeling incorporating anatomically accurate talus and tibia components, along with varying insert sizes, was utilized. Kinematic data acquired through dynamic radiostereometric analysis have been used as input in the FE model. Results showed that a congruent ankle prosthetic implant (all components of size 2) involves in a greater stability but also in concentrate contact pressures. This aspects could lead to a better proprioception of the patient but also to a faster insert wear over time. This underscores the importance of personalized insert sizing in TAA surgery, guided by patient-specific factors. Advanced imaging and computational tools facilitate precise preoperative planning and intraoperative decision-making. Optimal insert selection is crucial for improving long-term TAA outcomes.

Keywords: Contact pressure | FE model | RSA dynamic | TAA stability | Total ankle arthroplasty

Abstract: Nature-inspired metaheuristics have proven effective for addressing complex structural optimization challenges where traditional deterministic or gradient-based methods often fall short. This study investigates the feasibility and benefits of embedding three prominent metaheuristic algorithms, the Genetic Algorithm (GA), the Firefly Algorithm (FA), and the Group Search Optimizer (GSO) embedded into the ANSYS Parametric Design Language (APDL). The performance of each optimizer was assessed in three case studies. The first two are spatial truss structures, one comprising 22 bars and the other 25 bars, commonly used in structural optimization research. The third is a planar 15-bar truss in which member sizing and internal topology were simultaneously refined using a Discrete Topology (DT) variable method. For both the FA and the GSO, enhanced ranger-movement strategies were implemented to improve exploration–exploitation balance. Comparative analyses were conducted to assess convergence behavior, solution quality, and computational efficiency across the different metaheuristics. The results underscore the practical advantages of a fully integrated APDL approach, highlighting improvements in execution speed, workflow automation, and overall robustness.

Keywords: ANSYS APDL | finite element analysis | firefly algorithm | genetic algorithm | group search optimizer | nature-inspired metaheuristics | optimization

Abstract: The long-term effectiveness of osseointegrated implants is heavily dependent on the short-term stability, primarily achieved immediately after surgery through a mechanical connection between the bone and the implant. The most common implant designs nowadays are straight and rely on screw or press-fit fixtures. Despite the promising results achieved by current transfemoral implants, the incidence of early failures and complications is still high. Starting from the hypothesis that a patient-specific approach could lead to better primary stability immediately post-surgery, this study aims to investigate the effect of implant design on primary stability. This was performed by analyzing two patient-specific implants, customized according to the medullary canal morphology, and a simple straight implant as the reference standard. To quantitatively assess the primary stability, a comparative computational analysis was conducted to examine the effective contact area, the relative micromotion, and the stress distribution at the interface between the bone and the implant stem during a static load-bearing exercise. The results showed that implants that follow the curvature of the residual femur provide lower micromotion values and a wider contact area, with a reduction of up to 30.4% and an increase of 10.8%, respectively, compared to the straight design, leading to a more homogeneous load distribution.

Keywords: finite element analysis | load-bearing exercise | osseointegration | patient-specific design | primary stability | transfemoral implant

Abstract: The Reynolds-averaged Navier-Stokes (RANS) equations are the industry-standard computational fluid dynamics method for estimating forces, viscous effects, and boundary layer behaviour in various flow conditions, including adverse pressure gradients and flow-separation regimes. However, despite the ever-increasing availability of computational power, there are several scenarios in which more rapid methods, based on suitable simplified assumptions, offer advantages with respect to the RANS approach. Foil devices often operate at low angles of attack, high Reynolds numbers, and without fluid separation. These conditions make the Vortex Lattice Method (VLM) a viable and faster alternative for exploring the wide design space of yacht foils. In this study, the hydrodynamic forces generated by various foil geometries are computed using an original VLM formulation for generally curved lifting surfaces. The case study is focused on the foils of an ecofriendly dinghy designed and manufactured by students in the international framework of 1001VELAcup.

Keywords: CAD modelling | Computation fluid dynamics | Foil design | Vortex lattice method

Abstract: Cerebral aneurysm is a complex vascular pathology, and the assessment of its rupture risk is often based on qualitative criteria and clinical expertise. The present study aims to develop an objective parameter to support risk evaluation by integrating morphological and hemodynamic analyses. A novel morphological parameter has been introduced, combining key geometric features extracted from 3D vessel reconstructions of middle cerebral artery bifurcations. Computational fluid dynamics (CFD) simulations were conducted to analyze hemodynamic factors such as wall shear stress and intra-aneurysmal pressure, both of which are associated with aneurysm growth and rupture risk. Particular attention was given to defining physiologically accurate boundary conditions, essential for obtaining reliable results. The new morphological parameter alignment with clinical evaluations suggesting its potential to enhance the assessment of aneurysm operability and improve surgical decision-making.

Keywords: Cerebral aneurysm | CFD | Hemodynamics | Morphology

Abstract: The paper studies the behavior of homogeneous isotropic materials by performing appropriate numerical analyses and utilizing suitable FEMs to reproduce the Brazilian splitting test. Starting with a theoretical approach and adopting suitable numerical simulations, a new formula that is able to characterize the Young’s modulus is presented. To this end, in addition to the analysis of the specimen’s response in terms of stresses and strains, the real displacement field resulting from the real kinematical constraints on the specimen is determined. Therefore, the Brazilian test is taken as a reference test and the specimen’s behavior is derived by taking advantage of both the theoretical approach and numerical simulations developed in the ANSYS 2021 R1 environment. The latter allows us to define a new mathematical relation representing the missing part of the kinematical field. Furthermore, a new formula which explicitly relates the Young’s modulus of the material to the geometrical characteristics of the specimen, to the acting force, and to a measured selected displacement is proposed. Future developments will include adopting the proposed formulas for the identification of other mechanical parameters of the material, e.g.

Keywords: Brazilian splitting test | FEM | homogeneous isotropic material | kinematical behavior | mechanical parameter identification | nonuniform stress | numerical simulations

Abstract: This work presents a generative design algorithm for the semi-automatic reconstruction of sweepable surfaces from point clouds obtained through three-dimensional scanning. The proposed algorithm enables, starting from a 3D acquisition dataset, the correct automatic orientation of the mesh, the selection of a suitable cutting edge, and the specification of the number of transversal sections for an effective 3D model reconstruction. Additionally, it suggests a maximum number of points to be used for reconstructing the sectional curves. The mesh reconstruction is performed through a lofting operation, resulting in a non-uniform rational B-spline (NURBS) surface. The algorithm has been applied to a case study involving the front wing surface of a foil from the Olympic class iQFoil, which has recently garnered significant attention from researchers in the field of performance analysis. The obtained reconstructed surface exhibits very low deviation values when compared to the original mesh.

Keywords: 3D reconstruction | generative algorithm | innovative methods | iQFoil windsurfing foil

Abstract: As is widely recognized, advancements in new design and rapid prototyping techniques such as CAD modeling and 3D printing are pioneering individualized medicine, facilitating the implementation of new methodologies for creating customized orthoses. The aim of this paper is to develop a new automatic technique for producing personalized orthoses in a straightforward manner, eliminating the necessity for doctors to collaborate directly with technicians. A novel design method for creating customized wrist orthoses has been implemented, notably featuring a generative algorithm for the parametric modeling of the orthosis. To assess the efficacy of the developed algorithm, a case study was conducted involving the design and rapid prototyping of a wrist orthosis using Fused Deposition Modeling (FDM) technology. Subsequently, the developed algorithm was tested by clinicians and patients. The results obtained indicate that the implemented algorithm is user-friendly and could potentially enable non-expert users to design customized orthoses. These results introduce innovative elements of originality within the CAD modeling, offering promising solutions to the challenges associated with the design and production of customized orthoses. Future developments could consist of a better investigation regarding the parameters that influence the accuracy of the scanning and of the printing processes.

Keywords: additive manufacturing | CAD | generative design | reverse engineering | wrist orthosis

Abstract: The present paper is devoted to the proposal of appropriate numerical modelling able to provide a suitable description of the mechanical behavior of a composite geopolymer. Reference is made to a natural sisal-fiber-reinforced geopolymer. The study is based on the results of appropriate experimental investigations for compressive, flexural and splitting loadings, taking into account different weight percentages of fibers to evidence their role in the mechanical behavior. The main objective of the paper is to calibrate the microplane constitutive model, available in ANSYS software version 18.1, where the numerical analyses are performed. Therefore, the present study is structured in two different steps. Firstly, the mechanical behavior of geopolymers reinforced with sisal fibers is experimentally investigated, and subsequently, the gathered test data are interpreted and utilized to calibrate the relevant constitutive model to be used in the numerical stage. The obtained results are compared with experimental data, yielding good correlations. The paper’s results supply the parameters required to obtain an affordable numerical model of the reinforced geopolymer for different percentages of fibers to be adopted for material design with assigned mechanical properties.

Keywords: experimental tests | geopolymer composites | microplane model | numerical simulations | sisal fiber

Abstract: The process of designing a sail can be a challenging task because of the difficulties in predicting the real aerodynamic performance. This is especially true in the case of downwind sails, where the evaluation of the real shapes and aerodynamic forces can be very complex because of turbulent and detached flows and the high-deformable behavior of structures. Of course, numerical methods are very useful and reliable tools to investigate sail performances, and their use, also as a result of the exponential growth of computational resources at a very low cost, is spreading more and more, even in not highly competitive fields. This paper presents a new methodology to support sail designers in evaluating and optimizing downwind sail performance and manufacturing. A new weakly coupled fluid–structure interaction (FSI) procedure has been developed to study downwind sails. The proposed method is parametric and automated and allows for investigating multiple kinds of sails under different sailing conditions. The study of a gennaker of a small sailing yacht is presented as a case study. Based on the numerical results obtained, an analytical formulation for calculating the sail corner loads has been also proposed. The novel proposed methodology could represent a promising approach to allow for the widespread and effective use of numerical methods in the design and manufacturing of yacht sails.

Keywords: Computational fluid dynamics | Finite element method | FSI | Gennaker | Sail design | Sail loads

Abstract: The spreading of high computational resources at very low costs led, over the years, to develop new numerical approaches to simulate the fluid surrounding a sail and to investigate the fluid–structure interaction. Most methods have concentrated on upwind sails, due to the difficulty of implementing downwind sailing configurations that present, usually, the problem of massive flow separation and large displacements of the sail under wind load. For these reasons, the problem of simulating the fluid–structure interaction (FSI) on downwind sails is still subject of intensive investigation. In this paper, a new weak coupled procedure between a RANS solver and a FEM one has been implemented to study the FSI problem in downwind sailing configurations. The proposed approach is based on the progressive increasing of the wind velocity until reaching the design speed. In this way, the structural load is also applied progressively, therefore, overcoming typical convergence difficulties due to the non-linearity of the problem. Simulations have been performed on an all-purpose fractional gennaker. The new proposed method has been also compared with a classic weak FSI approach. Comparable results have been obtained in terms of flying shape of the gennaker and fluid-dynamic loads. The most significant characteristic of the proposed procedure is the easiness to find a solution in a very robust way without convergence problem, and also the capability to reduce the simulation time with regard to the computational cost.

Keywords: Computational fluid dynamics | Finite element method | Fluid–structure interaction | Gennaker | Interactive sail design | Mainsail

Abstract: Aim of this paper is presented a new methodology to study how different geometric parameters affect the performance of a hydraulic actuator. Preliminarily, the real working conditions of a hydraulic machine have been simulated by means of a CFD module. After, to test the reliability of the simulations, the obtained numerical results have been compared with the experimental data of a real prototype. This comparison demonstrates a good level of agreement between numerical and experimental results. Different simulations have been setup by modifying the actuator geometry and evaluating the efficiency of every analysed configuration. The results of this study give useful guidelines for the choice of the best geometry depending on the working conditions of the actuator.

Keywords: CAD model | CFD | Experimental analysis | Hydraulic actuator | Numerical simulation

Abstract: The use of glass fiber reinforced polymer materials (GFRP) has increased in recent years for structural engineering. The intrinsic non isotropic nature of GFRP materials together with many manufacturing characteristics encourages the extensive investigation of the real constitutive behaviour. Among the full-field contactless techniques electronic speckle-pattern interferometry (ESPI) plays an important role as a result of its capability to produce real-time fringe patterns on objects with optically rough surfaces, with a displacement sensitivity close to the light wavelength. The aim of this paper is to experimentally analyze the bending behaviour of GFRP specimens. This goal is achieved first by applying ESPI, handled by a phase-stepping technique, to obtain the experimental four-point flexural response of GFRP prismatic specimens with their longitudinal axis aligned with the pultrusion direction as well as with the orthogonal one. All the analysis are carried out by means of an in-plane set-up configuration and the images obtained are filtered by an appropriate developed iterative filter. The second step is to numerically reproduce the experimental behaviour by suitably setting the constitutive material model in an appropriate finite element code. The results obtained confirm that the GFRP material tested does not behave in an isotropic way and possesses a different Young's modulus in tension and compression.

Keywords: Displacement field | Glass fiber reinforced polymer materials | Pultruded material | Speckle interferometry

Abstract: In the present paper some experimental analyses of Dacron© 360 woven with and without surface treatment are presented to evaluate the effect of this treatment on the constitutive behaviour. This woven, widely adopted in sail manufacturing, is obtained by weaving polyethylene terephthalate (PET) yarn and it shows some peculiar features due to the manufacturing process. The experimental tensile tests, clearly show the orthotropy behaviour of the material. The effect of the treatment results in a stiffer behaviour especially along the warp and bias direction and in an increment of ultimate strength in all directions.

Keywords: Dacron | Mechanical behavior | Surface finish | Woven

Abstract: In this paper, the displacement field induced by the split-sleeve cold expansion of holes was measured using both digital image correlation (DIC) and digital speckle pattern interferometry (DSPI) techniques. Thus, the experimental results, which were evaluated on the inlet surface of a 6082-T6 aluminium plate, were compared with those from theoretical prediction. DIC provided accurate measurements up to the elastic-plastic boundary, whereas the DSPI technique highlighted the changes of displacement in the elastic domain. Prediction of the displacement based on the existing analytical model agreed with the experimental results achieved with both techniques. Possible explanations for the differences are discussed.

Keywords: cold expansion of holes | digital image correlation | digital speckle pattern interferometry | displacement measurement

Abstract: This paper presents the results of an extended method of measurement on a tyre for an off-road vehicle 175/82 R16, inserting Prescale paper at the contact with the ground. The experimental analysis of the pressures is carried out, in a cross-sectional direction, in five zones corresponding to the middle of the single dowels that constitute the tread. The results are analysed by means of suitable software so as to refer easily to the value of the pressure. The obtained results are critically analysed and the results are compared with those obtained by the formulae of Rowland and MacLaurin, and by the nominal pressure at the ground, concluding that the expression of MMP for vehicles on wheels is simply to consider a pointer of the performances, in comparison with other vehicles or wheels, rather than a real prediction of the pressure on the ground. Furthermore, a good agreement is found between the tyre deflection calculated and measured experimentally.

Keywords: Behaviour of the tyre | MMP | NGP | Prescale paper

Abstract: The propagation of an interface crack subjected to mixed mode I/II was investigated for two 2024-T351 aluminum thin layers joined by means of DP760 epoxy adhesive produced by 3M©. On the basis of beam theory, an analytical expression for computing the energy release rate is presented for the mixed-mode end loaded split (MMELS) test. The analytical strain energy release rate was compared by finite element (FE) analysis using the virtual crack closure technique (VCCT). Several fatigue crack growth tests were carried out in a plane bending machine to compare the experimental energy release rates to those of the analytical and FE solutions. Experimental results showed the relationship between the delamination modality and initial crack length rather than the applied load. The crack growth behavior showed stable crack growth followed by rapid propagation at the interface with the adhesive layer.

Keywords: Adhesive joint | Crack growth | Interface crack | MMELS specimen | Virtual crack closure technique

Abstract: This paper describes an approach to the keel design of a sailing yacht. The related software, which is fully automatic, leads to the optimal shape by modifying the surface used to define the keel planform. B-spline curves and surfaces have been used due to their ability in following complex shapes. The algorithm integrates ad hoc implemented original software with computational fluid dynamics (CFD) commercial ones. The optimisation procedure uses genetic algorithms (GAs) and a gradient-based optimiser for the refinement of the solution. A careful CAD and CFD modelling leads to a stable and efficient generalised method, which has been applied to the design of the centreboard of the 5o5 international class racing dinghy.

Keywords: CFD | Design optimisation | GAs | Sailing yacht

Abstract: A numerical procedure, which combines two hybrid finite element formulations, was developed to analyse the stress intensity factors in cracked perforated plates with a periodic distribution of holes and square representative volume elements. The accuracy of the method in predicting the stress intensity factor was verified by a comparison with experimental measurements, carried out by a photoelasticity method, and by commercial finite element software. Several simulations were executed by varying both the crack length and the hole diameters, and the effects of the holes on the stress intensity factor are illustrated. The method shows high accuracy and efficiency, as small differences were observed when compared with the traditional finite element method, notwithstanding a strong reduction in degrees of freedom and mesh complexity.

Keywords: Hybrid finite element | Perforated plate | Photoelasticity | Stress intensity factor

Abstract: In the paper the results of a wide range of experiments on friction stir welding (FSW) of aluminium alloys are reported. In particular, the AA6082-T6 butt joints fatigue resistance was investigated by varying the most relevant process parameters. In addition, a revolutionary pitch was utilized in order to investigate the effects of the tool rotating speed and the tool feed rate. Observations of the fracture insurgence were developed for different levels of applied load.

Keywords: Aluminium alloys | Fatigue resistance | Friction stir welding

Abstract: This paper deals with the influence of matrix cracks on the failure mode of bimaterial systems and composite materials. In order to investigate such an influence, the stress field near a crack embedded into the more yielding material and propagating perpendicularly to the interface, has been analyzed by using systematic numerical simulations. Such analysis has shown that the crack propagation give rises to transversal stresses that can damage the reinforcing materials when this has low modulus, as glass fibers, or low transversal strength, such as carbon fibers. Moreover, the longitudinal stress concentration can damage the reinforcing material only if this has high stiffness, as in the case of aramid and carbon fibers. Also, the numerical results have permitted to implement simple formulas that allows the user an accurate evaluation of the SIF as well as to predict possible debonding or fiber splitting phenomena. Finally, the SIFs evaluated numerically have been corroborated by experimental tests carried out by using an efficient procedure based on RGB digital photoelasticity.

Keywords: Bimaterial systems | Boundary element method | Fracture mechanics | Photoelasticity | Stress intensity factor