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Hybrid fiber‐reinforced composite sandwich panels with multi‐layer polyurethane cores are widely applied in aerospace, automotive, construction, and shipbuilding industries. This study aims to investigate the buckling performance of composite structures with varying numbers of polyurethane cores. To achieve this, the buckling loads of these structures are determined using an energy method, microscopic mechanics method, and the first‐order zigzag kinematic model. The accuracy of the equation employed in the algorithm is validated using the finite element method. Additionally, we conduct a parametric analysis to examine the influence of various parameters on the buckling performance of the structures. The results indicate that an effective strategy for improving the critical buckling loads of the hybrid fiber‐reinforced composite sandwich plate involves strategically placing fibers and matrix materials with higher elastic modulus on the skin layer. Moreover, the critical buckling load is notably influenced by the number and positioning of polyurethane layers, as well as the fiber content. Highlights: An analytical model is established to predict the buckling behavior.The correctness of the model was verified using the finite element method.Effects of structural parameters on buckling performance were investigated. [ABSTRACT FROM AUTHOR]

In this study, under the conformity of engineering reality, considering the influence of slip coefficient on the variation range of winding angle, 15 composite lay‐up schemes of hydrogen storage vessels were designed using grid theory, and the hydrogen storage vessels's structural strength was analyzed. The distribution of non‐geodesic fiber windings on the outer surface of the inner layer was solved using differential theory and the winding principle, and ABAQUS established the finite element model. The maximum stress value and stress distribution of the composite layer of the hydrogen storage vessel along the fiber direction were studied, the damage of the composite layer was analyzed, and the pressure and mode of the bursting were predicted. Results show that the structural strength of the hydrogen storage vessel designed by this method can be effectively guaranteed. The hoop winding layer bears the majority of the stress on the hydrogen storage vessel, while the helical winding layer's fiber strength is not entirely utilized. The hydrogen storage vessel gains greater structural strength when the circumferential winding layer is concentrated and situated at the outermost portion of the composite layer. The layup scheme has an impact of approximately 17.21% on burst pressure. Highlights: Effect of slip coefficient on the change of winding angle.Different forms of composite lay‐up schemes were designed.The stress distribution in the composite layer was studied.Analyzed structural strength and damage of the composite layer.Predicted the pressure and mode of bursting. [ABSTRACT FROM AUTHOR]

Background: The surgical treatment for mandibular repositioning using a bilateral sagittal split osteotomy (BSSO) favours the development of techniques that result in adequate repair and stability. In Puricelli's mandibular sagittal split osteotomy (PMSSO) proposal, the vertical lateral cut osteotomy is located in the interradicular space between the lower first molar and second premolar. Objectives: This in silico study aimed to investigate the mechanical stability of PMSSO and compare it with the classical Obwegeser–Dal Pont technique for mandibular advancement. Materials and methods: A computational geometric model of the mandible was created in a virtual environment using computer-aided design (CAD) software. After reproducing the advancements, two test groups were developed: GTOD10, Obwegeser–Dal Pont osteotomy, and GTP10, Puricelli osteotomy, both simulating a 10-mm mandibular advancement, allowing for measuring the area of overlap between bone segments. With the geometric changes promoted by the osteotomy, boundary conditions of displacement and force were applied to a CAD software based on finite element analysis (FEA), allowing for quantitative and comparative analysis of the stress and vertical displacement of the mandible, mechanical measurements that may be associated with strength and stiffness. Results: A 17.48% higher stress was observed in the GTP10 group than in GTOD10. However, the region of highest stress in GTP10 was found in a part of the bone that was still intact and far from the area of fragility caused by lateral vertical osteotomy. In contrast, in GTOD10, the region with high stress was in a less resistant bone region. The GTP10 group showed a 28.73% lower displacement than GTOD10. The area of overlap between the proximal and distal segments of the mandible was 33.13% larger in the GTP10 than in the GTOD10 group. Conclusion: The PMSSO method, performed in large mandibular advancements, keeps the point of highest stress away from the mandibular fragility zone. Considering the same amount of advancement, it also promotes less displacement and larger areas of bone overlap. Clinical relevance: The results suggest that PMSSO, applied in large mandibular advancement, presents greater postoperative stability. [ABSTRACT FROM AUTHOR]

Healing of tibia demonstrates a complex mechanobiological process as it is stimulated by the major factor of strains applied by body weight. The effect of screw heads and bodies as well as their pressure distribution is often overlooked. Hence, effective mechanical conditions of the healing process of tibia can be categorized into the material of the plate and screws, post‐operation loadings, and screw type and pressure. In this paper, a mathematical biodegradation model was used to simulate the PGF/PLA plate‐screw device over 8 weeks. The effect of different post‐operation loading patterns was studied for both locking and non‐locking screws. The aim was to reach the best configuration for the most achievable healing using FEA by computing the healing pattern, trend, and efficiency with the mechano‐regulation theory based on deviatoric strain. The biodegradation process of the plate and screws resulted in 82% molecular weight loss and 1.05 GPa decrease in Young's modulus during 8 weeks. The healing efficiency of the cases ranged from 4.72% to 14.75% in the first week and 18.64% to 63.05% in the eighth week. Finally, an optimal case was achieved by considering the prevention of muscle erosion, bone density reduction, and nonunion, according to the obtained results. [ABSTRACT FROM AUTHOR]

The utilization of cold-formed thin-walled members as structural members has gained significant popularity due to their advantages in fabrication, cost-effectiveness, and transportation convenience. However, the reduced thickness of the used sections poses challenges such as global, local, and distortional member buckling, leading to a decrease in their axial strength. This study focuses on addressing these challenges by connecting the channels together using screws as an alternative to welding, considering the cost, time, and ease of implementation. Conducting finite element analysis on structural columns built-up from cold-formed double C steel channels and subjected to axial loads, this paper verifies the numerical models used against experimental tests known from the literature. A comparison of experimental results with nonlinear FEA and AISI & AS/NZ standards reveals commendable agreement, particularly in predicting the buckling behavior of the built-up I-shaped CFS columns. While the results of the finite element analysis show an overestimation of approximately 3.6% compared to the experimental tests, the AISI and AS/NZS standards demonstrate a conservatism of about 3.0%. Furthermore, the current study investigates the influence of screw spacing on axial strength of built-up cold-formed steel columns. The findings are derived from 175 finite element experiments, evaluating seven different cross-sectional profiles with twelve distinct screw spacings. These spacings correspond to the half-wavelength of local, distortional, and global buckling, divided by values ranging from one to four. The screw spacing determined by half the local buckling half-wavelength along the webs' centerline resulted in enhancements of 22%, 7%, 13%, and 11% in the critical elastic local, distortional, and global column buckling loads, as well as the nominal axial strength, respectively. These increases were even more pronounced for double-lane fasteners with the same spacing, yielding improvements of 25%, 46%, 17%, and 12%, respectively. For economic considerations, it is advisable to utilize single-lane fasteners with a half-wavelength equal to half the local buckling half-wavelength. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSOne of the remaining challenges for advancing the wide application of composite materials is to further improve the mechanical properties of composites. The fiber/matrix damage phenomenon produced by the composite model under axial loading has been observed through the establishment of a numerical model of composite damage. Axial crush tests have been performed on C-type carbon fiber reinforced polymers (CFRP) stanchions for the cargo floor structure of transport category airplanes using a finite element approach. The failure morphology and crashworthiness parameters of the specimens with different fiber layups have been recorded, and the effects of fiber orientation and angle of entrapment on the crashworthiness of the composites have been investigated. The present study demonstrates that the crashworthiness of composites can be effectively improved by fiber orientation design. Appropriate addition of 45° layer and 90° layer can effectively improve the crashworthiness of C-type CFRP laminates, and the performance of the two-angle and spiral laminates design is improved by 26% and 19%, respectively.The effect of stacking sequences on the crashworthiness of thin-walled C-type CFRP structures was investigated.The crashworthiness index and failure morphology of CFRP specimens with different fiber layup angles, layup sequences and pinch angles were analyzed.Several sets of fiber layup combinations with superior impact properties were derived from comparative analyses.A theoretical model is proposed to reveal the mechanism of the influence of different fiber layups on the crashworthiness and energy-absorbing properties of C-type CFRP. [ABSTRACT FROM AUTHOR]

The notch effect of semicrystalline PVDF was investigated using U- and V-notch geometries with different depths, and tensile tests were performed at 23 °C using the DIC technique and FEA. Both unnotched and notched dumbbell-shaped specimens were subjected to tensile loading with the DIC technique to obtain mechanical curves and strain maps. The experimental data were compared to a numerical model, analyzing both global mechanical curves and local strain maps around the notch region to assess the accuracy of the simulations. The results demonstrated that the geometry and depth of the notch influence the mechanical behavior of PVDF, presenting a decrease in load and displacement compared to unnotched specimens. This aspect was corroborated by strain maps, which showed the increase in the local strain around the notch tip. For FEA, the global analysis indicated a good correlation with experimental results, and the local analysis demonstrated a reasonable agreement in strain map results within 0.5 mm of the notch neighborhood. Overall, the DIC technique and FEA provided a reliable evaluation of notch behavior on the PVDF used as pressure sheaths with reasonable precision. [ABSTRACT FROM AUTHOR]

The paper presents a finite element method (FEM) analysis of composite hexagonal honeycomb structures, which are widely used in various engineering applications due to their high strength-to-weight ratio and energy absorption capabilities. The primary objective is to investigate the mechanical behavior and performance of these structures under loading conditions. By employing advanced FEM techniques, a model in SolidWorks is created, and the hexagonal honeycomb configurations are simulated using composite materials and Hypermesh to understand their stress distribution, deformation characteristics and failure mechanisms. The study includes parametric analysis to evaluate the effects of various factors such as cell wall thickness, material properties and geometric dimensions on the overall structural integrity. The findings provide valuable insights into optimizing honeycomb structures for enhanced performance in aerospace, automotive and civil engineering applications and contribute a model for four distinct types of material. [ABSTRACT FROM AUTHOR]

Due to their extraordinary qualities, including fire resistance, excellent crashworthiness, low thermal conductivity, permeability, non-toxicity, and reduced density, cellular materials have found extensive use in various engineering applications. This study uses a finite element analysis (FEA) to model the dynamic compressive behaviour of agglomerated cork to ascertain how its material density and stress relaxation behaviour are related. Adding the Mullins effect into the constitutive modelling of impact tests, its rebound phase and subsequent second impact were further examined and simulated. Quasi-static and dynamic compression tests were used to evaluate the mechanical properties of three distinct agglomerated cork composite samples to feed the numerical model. According to the results, agglomerated cork has a significant capacity for elastic rebound, especially under dynamic strain rates, with minimal permanent deformation. For instance, the minimum value of its bounce-back energy is 11.8% of the initial kinetic energy, and its maximum permanent plastic deformation is less than 10%. The material's model simulation adequately depicts the agglomerated cork's response to initial and follow-up impacts by accurately reproducing the material's dynamic compressive behaviour. In terms of innovation, this work stands out since it tackles the rebounding phenomena, which was not previously investigated in this group's prior publication, either numerically or experimentally. Thus, this group has expanded the research on cork materials' attributes. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvesters (PEHs) have drawn considerable attention due to their unique ability to convert ambient mechanical energy to electrical energy. These devices are widely implemented in numerous applications such as wearable technology, structural health monitoring, and renewable energy systems. In this work, a novel approach that seamlessly integrates arbitrary metastructures into the substrate layer of cantilever beam‐based PEHs is presented. The corresponding performance of each PEH design is evaluated via an experimentally validated finite element model. This is the first systematic study to explore 3D metastructures with various unit cell configurations, unit cell numbers, and porosity levels. Compared with the existing PEH designs, implementation of a 3D auxetic metastructure with 85% porosity single unit cell design can demonstrate a substantial enhancement in output power, reaching 48.16 mW, and a high normalized power density (NPD) of 2.1131 µW mm−3 g−2 Hz−1. Results show that there are competing requirements for improving the performance of PEHs. On one hand, low metastructure stiffness is preferred to achieve high power output at low resonant frequency. On the other hand, metastructures designs with low stiffness may induce excessive distortion in the substrate layer, leading to mechanical energy loss. This deformation mechanism adversely affects the mechanical to electrical energy conversion efficiency. Detailed guidelines for designing and manufacturing high‐performance PEHs are discussed in this work. [ABSTRACT FROM AUTHOR]

Flexible thermoelectric (TE) materials that convert heat into electricity have been widely used in wearable electronics and other flexible devices. In this work, inorganic TE pillars were combined with thermoplastic polyurethane (TPU) to assemble a flexible string-shaped TE generator (TEG) for the fabrication of the thermoelectric fabric (TEF). Moreover, finite element analysis (FEA) was used to optimize the dimensions of the TE string and evaluate its performance. The FEA results showed that the inter-pillar spacing significantly affected the temperature difference, the output voltage and the internal resistance. A maximum power density of 3. 43 μW/cm² (temperate gradient ΔT = 10. 5 K) was achieved by the TE string with a diameter of 3. 5 mm and an inter-pillar spacing of 2 mm. However, under the experimental condition, the achievable power density of the fabricated three-dimensional (3D) TEF was limited to 29% of the simulation result because of the inclination of the TE string within the fabric concerning heat plate contact and copper wire-TE pillar connections. The actual TE string also demonstrated high flexibility and stable mechanical properties after 450 bending cycles. Thus, the study would provide a foundation for future research in developing more efficient TEFs to offer a comfortable and conformable option for wearable energy harvesting applications. [ABSTRACT FROM AUTHOR]

In China's Yangtze River and Yellow River basin cotton-growing regions, the complex terrain, scattered planting areas, and poor adaptability of the existing machinery have led to a mechanized cotton harvesting rate of less than 10%. To address this issue, we designed a crawler chassis for a brush-roller cotton harvester. It is specifically tailored to meet the 76 cm row spacing agronomic requirement. We also conducted a theoretical analysis of the power transmission system for the crawler chassis. Initially, we considered the terrain characteristics of China's inland cotton-growing regions and the current cotton agronomy practices. Based on these, we selected and designed the power system and chassis; then, a finite element static analysis was carried out on the chassis frame to ensure safety during operation; finally, field tests on the harvester's operability, stability, and speed were carried out. The results show that the inverted trapezoidal crawler walking device, combined with a hydraulic continuously variable transmission and rear-drive design, enhances the crawler's passability. The crawler parameters included a ground contact length of 1650 mm, a maximum ground clearance of 270 mm, a maximum operating speed of 6.1 km/h, and an actual turning radius of 2300 mm. The maximum deformation of the frame was 2.198 mm, the deformation of the walking chassis was 1.0716 mm, the maximum equivalent stress was 216.96 MPa, and the average equivalent stress of the entire frame was 5.6356 MPa, which complies with the physical properties of the selected material, Q235. The designed cotton harvester crawler chassis features stable straight-line and steering performance. The vehicle's speed can be adjusted based on the complexity of the terrain, with timely steering responses, minimal compaction on cotton, and reduced soil damage, meeting the requirements for mechanized harvesting in China's inland small plots. [ABSTRACT FROM AUTHOR]

A ply-level based modeling strategy for predicting the delamination behavior of laminated composites under pure and mixed mode loading conditions is implemented within the framework of the Finite Element Method. Each ply and each interface of the laminate is explicitly modeled, with the plies represented by various element types such as conventional shell, continuum shell, and continuum elements, and the interfaces are discretized using cohesive zone elements. The comparison between all models is examined in terms of delamination onset and growth including load-displacement curves, delamination area, computation time, and mode-mixity. The results show that all ply-level based modeling strategies exhibit very good agreement with the analytical results. Moreover, ply-level approach based on shell elements in combination with finite thickness cohesive zone elements offers a numerically efficient simulation tool to predict delamination behavior in laminates. [ABSTRACT FROM AUTHOR]

This study explores the mechanical and morphological properties of architectured lattices, driven by additive manufacturing advancements, and compares different finite element analysis (FEA) methods that are often used to predict the mechanical behavior and failure mechanisms of these lattices. FEA methods based on various material models, including Homogenization (AH), Arruda-Boyce (AB), Yeoh hyperelastic (YH), and Johnson–Cook (JC), are compared to address limitations in classical models, such as the classical rubber elasticity model, the Ogden model, and the polynomial model, with respect to experimental verification under uniaxial compression testing of additively manufactured poly ether ether ketone (PEEK). PEEK lattices with 50% porosity were produced via fused filament fabrication (FFF) utilizing triply periodic minimal surface (TPMS) structures based on two specific unit cell geometries: gyroid and diamond. Our analysis, involving both elastic and yielding regions, revealed the superiority of the JC model in predicting the mechanical properties of gyroid-based lattice structures and the superiority of the AB model for diamond-based lattices. This study highlights the crucial role of material models in the computational analysis of lattice structures' mechanical behavior. Discrepancies observed between computational and experimental outcomes are attributed to manufacturing defects and constraints in the material models employed. [ABSTRACT FROM AUTHOR]

Highlights This paper investigates a honeycomb sandwich structure that draws inspiration from the craft of origami. A specific folding pattern was applied to the honeycomb to create the origami‐based re‐entrant honeycomb (ORH), aimed at improving the energy absorption properties of the sandwich structure. The study on the energy absorption properties of structures under low‐velocity impact (LVI) utilized both experimental and numerical approaches. The energy absorption properties of the sandwich structure were examined by conducting LVI tests with different impact energy and then compared to the mechanical properties of the traditional re‐entrant honeycomb sandwich structures (TRHSS). Additionally, a refined finite element model has been established and its accuracy verified. Numerical studies were conducted to explore the effects of structural parameters on the energy absorption properties of ORH sandwich structure (ORHSS). The results show that the ORHSS exhibited a significant reduction in peak force when subjected to LVI, in contrast to the TRHSS. Furthermore, the ORHSS exhibit significant efficiency in energy absorption. Enhancing the wall thickness t$$ t $$ or folding angle V/H$$ V/H $$ can significantly improve the energy absorption properties of the ORHSS, thereby boosting the honeycomb's contribution to this process. This optimization results in an improved absorptive effect of the structure. The findings offer new recommendations for developing lightweight absorbent materials with potential applications across various industries. A novel composite sandwich structure serves as an efficient device for absorbing energy. This sandwich structure exhibits excellent cushioning and energy absorption capabilities. Changing geometric parameters can enhance the impact performance of the structure. A larger folding angle V/H$$ V/H $$ makes the core more prone to deformation. The greater the forward length V$$ V $$ of the ORH, the lower specific energy absorption (SEA) of the ORHSS. [ABSTRACT FROM AUTHOR]

In this study, a plane strain finite element analysis (FEA) was employed to investigate failure mechanisms of a hydrogen storage pipe system made of 316L stainless steel pipe coated with pure and functionally graded (FG) ceramic layers composed of Al2O3 and SiC. The system was studied for different common failure mechanisms, i.e., delamination, surface cracking and buckling delamination, upon cooling from an elevated stress-free temperature. Finally, the composition and thickness of the coating layers were considered as the main controlling factors and investigated for their influence on the studied failure mechanisms. It was observed that the most energetically favourable cracking mechanism for this type of system was surface cracking with the propagation of these cracks eventually leading to different failure paths. Buckling was found to be as less energetically favourable compared to surface cracking with the buckling resistance being enhanced by changing the coating thickness and composition factor. [ABSTRACT FROM AUTHOR]

AbstractThis study aimed to evaluate the material properties of four dental cements, analyze the stress distribution on the cement layer under various loading conditions, and perform failure analysis on the fractured specimens retrieved from mechanical tests. Microhardness indentation testing is used to measure material hardness microscopically with a diamond indenter. The hardness and elastic moduli of three self-adhesive resin cements (SARC), namely, DEN CEM (DENTEX, Changchun, China), Denali (Glidewell Laboratories, CA, USA), and Glidewell Experimental SARC (GES—Glidewell Laboratories, CA, USA), and a resin-modified glass ionomer (RMGI—Glidewell Laboratories, CA, USA) cement, were measured using microhardness indentation. These values were used in the subsequent Finite Element Analysis (FEA) to analyze the von Mises stress distribution on the cement layer of a 3D implant model constructed in SOLIDWORKS under different mechanical forces. Failure analysis was performed on the fractured specimens retrieved from prior mechanical tests. All the cements, except Denali, had elastic moduli comparable to dentin (8–15 GPa). RMGI with primer and GES cements exhibited the lowest von Mises stresses under tensile and compressive loads. Stress distribution under tensile and compressive loads correlated well with experimental tests, unlike oblique loads. Failure analysis revealed that damages on the abutment and screw vary significantly with loading direction. GES and RMGI cement with primer (Glidewell Laboratories, CA, USA) may be suitable options for cement-retained zirconia crowns on titanium abutments. Adding fillets to the screw thread crests can potentially reduce the extent of the damage under load. [ABSTRACT FROM AUTHOR]

Thermoplastic composites have a high application demand in aerospace, marine military and other cutting‐edge industry. However, it poses a considerable obstacle in achieving three‐dimensional (3D) thermoplastic composites because of the inadequate infiltration of highly viscous thermoplastic resins. In this paper, high‐toughness Polyetheretherketone (PEEK) resin‐based 3D orthogonal carbon fiber thermoplastic composites were designed and obtained. Low‐velocity impact test was conducted on 3D orthogonal woven composite (3DOWC) under the energy levels of 5 and 10 J, and its performance was compared with that of the 2D unidirectional layup composite (2DULC) and the 2D plain layup composite (2DPLC). The results showed that 3DOWC possessed superior elastic energy absorption capacity and less damage morphology compared to 2D composites. 3DOWC had the highest contact force value of 2420.25 N at 10 J, which is 36.83% higher than that of 2DPLC. Furthermore, a finite element model in multi‐scale was established to investigate the damage evolution and failure mechanism of the 3D orthogonal woven CF/PEEK composites. The damage morphology observed in both experimental and numerical findings demonstrated that the matrix shedding, while the yarn fractured on the nonimpact side beneath the impact point. Additionally, enhancing the tensile strength of the yarn in the bottom layer can lead to further improvement in impact resistance. This work provides an innovative method for manufacturing 3D thermoplastic composites and lays the foundation for the impact simulation analysis of such composites. Highlights: A novel approach was introduced for fabricating 3D carbon fiber/PEEK composites, which exhibits remarkable resistance to impact.A comprehensive investigation was conducted to evaluate the impact properties of 3D thermoplastic composite compared to 2D composite.A finite element model in multi‐scale including failure criteria was established to simulate the damage evolution. [ABSTRACT FROM AUTHOR]

User expects his weapon to be light and reliable and to perform multiple times firing per unit time at the same time. In today's technology, the maximum number of firings can be made per unit time with steel barreled weapons, but in composite barrels; many problems occur due to overheating, strength and reliability. Meeting these opposite demands is an engineering problem. In this study, the design of a composite‐steel combination light gun barrel is studied. Firstly, pressure distribution through the barrel has been calculated using Vallier‐Heydenreich method. According to the calculations, analysis has been conducted using both steel barrel and composite barrel. After the analysis, a composite barrel has been manufactured and testing has been conducted on an all‐steel barrel and the manufactured composite barrel. Composite is carbon fiber and resin is epoxy resin. In composite material, carbon fiber is preferred at the rates of 50% and 60%, the material of the steel barrel is AISI 416R stainless steel. The manufactured steel barrels have the same outer diameter but different wall thickness ratios, firing tests were conducted in such a way that the number of shots per unit time was the same. Highlights: Stress distribution within a gun barrel was calculated using Vallier‐Heydenreich method.Design and finite element analysis analysis for an all‐steel gun barrel and a composite gun barrel was conducted.A composite gun barrel was manufactured; by using composite materials, the barrel was lightened by 24.8%.The manufactured composite gun barrel and an all‐steel gun barrel were tested by firing over 2500 shots. [ABSTRACT FROM AUTHOR]

AbstractThis article proposes a glass fiber reinforced plastic (GFRP) wave spring and conducts a study on its free and constrained vibration characteristics and compression performance. Initially, a stiffness prediction model for composite wave spring is established using laminated plate theory and Moore’s theorem. Additionally, the failure mode of the composite wave spring was predicted and experimentally confirmed using ABAQUS and the 3D-Hashin failure criterion. Finally, the vibration characteristics of composite wave spring and metal helical spring are investigated using the B&K testing system in both free and constrained states. The experimental stiffness and ultimate load of the composite wave spring are 20.67 N/mm and 1386.67 N. The composite wave spring exhibits good vibration reduction performance in both free and constrained states, with maximum vibration attenuation amplitudes of 122.71 and 144.93 dB. In comparison, the metal helical spring has maximum vibration attenuation amplitudes of 41.65 and 111.89 dB. [ABSTRACT FROM AUTHOR]

This study develops a sophisticated three-dimensional elastoplastic progressive damage finite element analysis (FEA) model for stiffened composite materials under axial compression. The model integrates the Hashin and Ye criteria to capture the inception of damage within the composite and introduces a cohesive zone model (CZM) to simulate debonding between stiffeners and panels. Furthermore, damage evolution based on energy release rate and plastic flow rules grounded in Hill’s criteria are employed to thoroughly explore the progressive failure behavior of stiffened composite materials. Implemented within Abaqus/Explicit through user-defined ‘VUMAT’ subroutines, the model ensures computational accuracy and reliability. Comparative evaluations against standard linear elastic progressive damage models demonstrate a statistically significant improvement of at least 5% in predicting ultimate load capacities. Additionally, this model accurately captures different failure modes, providing a nuanced understanding of stiffened composite material failure under compressive loads. [ABSTRACT FROM AUTHOR]

Due to its excellent aerodynamic performance and relatively light weight, the V-tail has a wide range of applications in high aspect ratio and long endurance integrated unmanned aerial vehicles(UAV). Lightweight design is the main way to improve the endurance of unmanned aerial vehicles. Based on response surface methodology, the wingspan length, number of ribs, and skin thickness of the designed V-tail were optimized, resulting in a new V-tail configuration. Through strength verification, modal analysis, and external flow field simulation analysis, the results show that the newly obtained V-shaped tail can maintain relatively stable aerodynamic performance while meeting the requirements of strength and structural dynamic characteristics, and the structural quality is reduced by 22. 88% compared to before optimization. Finally, the lightweight V-tail design was successfully prototyped using fused deposition modeling(FDM) additive manufacturing technology, and the experimental results confirmed a weight reduction consistent with the simulation findings, validating the feasibility of the optimization approach. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive finite element analysis (FEA) of pre-stressed Ultra High-Performance Concrete (UHPC) girders, showcasing intricate structural behaviors under various loading conditions. Utilizing advanced finite element modeling techniques, the study accurately simulates the flexural response of UHPC girders, integrating experimental results from large-scale laboratory tests conducted by researchers at the Turner-Fairbank Highway Research Center. This paper shows the effectiveness of simulating pre-stressing forces via initial equivalent temperature load with relatively accurate stress and strain predictions. The paper also delves into the moment–deflection relationships at critical stages, such as first concrete crack appearance, yielding, and strain localization, to capture the non-linear behavior of UHPC girders under pre-stressed conditions. Additionally, crack propagations were characterized by investigating the damage in tension (DAMAGET) plots. In summary, the results of the finite element model agree well with the experimental observations. Moreover, this study not only demonstrates the effectiveness of FEA in accurately simulating the complex structural behaviors of UHPC girders but also highlights its broader applicability to the design and analysis of other girder types, offering valuable insights compared to ordinary concrete beams. [ABSTRACT FROM AUTHOR]

The efficient mitigation of acoustic disturbances is essential for various applications. The primary purpose of this work is to investigate how structural parameters of a hybrid acoustic structure, integrating 3D-printed perforated panels and open-pore polyurethane foam, influence its sound absorption properties. Various configurations of this acoustic structure were examined, maintaining a consistent total thickness of 25 mm but varying individual layer thicknesses. Panel thicknesses ranged from 0.5 mm to 2.0 mm, with corresponding foam layers adjusted to maintain the overall thickness. Perforation diameters ranged from 0.5 mm to 2.0 mm, and the number of holes varied systematically between 50 and 250. The focus was on lower frequencies up to 2000 Hz. The 1/3rd octave frequency bands were used to quantify the Sound Absorption Coefficient, with the Noise Reduction Coefficient used for a holistic understanding of acoustic properties. The acoustic performance exhibited frequency-dependent behaviour, generally peaking in the mid-frequency range. Notably, the Noise Reduction Coefficient ranged between 0.1510 and 0.4786 across different configurations. Peak absorption was observed between 630 Hz and 1250 Hz for most configurations, with particular structures achieving coefficients as high as 0.99. The number of perforations, hole diameter, and panel thickness played crucial roles in influencing the sound absorption properties, allowing for tailored acoustic solutions. Combining polyurethane foam and 3D-printed perforated panels provides a promising approach for efficient sound absorption for a specified frequency range. This study offers a comprehensive understanding of the influence of structural parameters on sound absorption capabilities, laying the groundwork for optimized, application-specific acoustic solutions. [ABSTRACT FROM AUTHOR]

Effective sound absorption is crucial in environments like schools and hospitals. This study evaluates open-pore polyurethane foam and perforated onyx panels, which attenuate noise via distinct mechanisms: porous materials convert sound energy to heat through viscous and thermal losses, while perforated panels use resonant behaviour for energy dissipation. The impact of hole geometries and panel orientations on the sound absorption coefficient and noise reduction coefficient was investigated using COMSOL Multiphysics 6.0 for finite element analysis and ISO 10534-2 compliant impedance tube experiments. Six perforated panel configurations were 3D-printed with varying hole diameters and backed by a 24 mm polyurethane foam layer. Both 'forward' and 'reverse' configurations were assessed. A tapered hole from 4 mm to 2 mm showed the highest sound absorption across the 100–4000 Hz range, with a noise reduction coefficient of 0.444, excelling in both orientations. Reverse designs generally performed less, underscoring the importance of hole geometry and orientation. Experimental results aligned with FEA simulations, validating the computational model. This study elucidates sound absorption mechanisms of porous and perforated materials, providing a validated framework for material selection in noise-sensitive settings and highlighting 3D-printing's potential in noise control. [ABSTRACT FROM AUTHOR]

Air-backed fiber optic mandrel hydrophones are being used in typical remotely interrogated phase interferometric sensor arrays for underwater acoustic surveillance applications. This paper is focused on the design of a new air-backed large-aperture composite mandrel hydrophone having a metallic inner tube and a composite foaming layer. A comprehensive set of hydrophone cases were selected and analyzed using finite element analysis (FEA) with varying geometric and material mechanical parameters. Using FEA, we evaluated strain distributions and natural frequency, computed pressure sensitivity and achieved optimum hydrophone configurations, having an omnidirectional directivity pattern. Its elliptic-cylinder streamlined shape with structural stability even up to 400 m depth of operation makes it well suited for submarine sonar flank arrays. The vital requirements of waterproof underwater packaging, customized fabrication details and the concept of easy array realization are also addressed. [ABSTRACT FROM AUTHOR]

Abstract Background The surgical treatment for mandibular repositioning using a bilateral sagittal split osteotomy (BSSO) favours the development of techniques that result in adequate repair and stability. In Puricelli’s mandibular sagittal split osteotomy (PMSSO) proposal, the vertical lateral cut osteotomy is located in the interradicular space between the lower first molar and second premolar. Objectives This in silico study aimed to investigate the mechanical stability of PMSSO and compare it with the classical Obwegeser–Dal Pont technique for mandibular advancement. Materials and methods A computational geometric model of the mandible was created in a virtual environment using computer-aided design (CAD) software. After reproducing the advancements, two test groups were developed: GTOD10, Obwegeser–Dal Pont osteotomy, and GTP10, Puricelli osteotomy, both simulating a 10-mm mandibular advancement, allowing for measuring the area of overlap between bone segments. With the geometric changes promoted by the osteotomy, boundary conditions of displacement and force were applied to a CAD software based on finite element analysis (FEA), allowing for quantitative and comparative analysis of the stress and vertical displacement of the mandible, mechanical measurements that may be associated with strength and stiffness. Results A 17.48% higher stress was observed in the GTP10 group than in GTOD10. However, the region of highest stress in GTP10 was found in a part of the bone that was still intact and far from the area of fragility caused by lateral vertical osteotomy. In contrast, in GTOD10, the region with high stress was in a less resistant bone region. The GTP10 group showed a 28.73% lower displacement than GTOD10. The area of overlap between the proximal and distal segments of the mandible was 33.13% larger in the GTP10 than in the GTOD10 group. Conclusion The PMSSO method, performed in large mandibular advancements, keeps the point of highest stress away from the mandibular fragility zone. Considering the same amount of advancement, it also promotes less displacement and larger areas of bone overlap. Clinical relevance The results suggest that PMSSO, applied in large mandibular advancement, presents greater postoperative stability.

Abstract Atomic Force Microscopy (AFM) is a leading nanoscale technique known for its significant advantages in the analysis of soft materials and biological samples. Traditional AFM data analysis is often based on the Hertz model, which assumes perpendicular indentation of a planar sample. However, this assumption is not always valid due to the varying geometries of soft materials, whether natural, synthetic or biological. In this study, we present a new theoretical model that incorporates correction coefficients into Hertz’s model to account for cone-like and spherical probes, and to consider local tilt at the probe-sample interface. We validate our model using finite element analysis (FEA) simulations and experimental AFM measurements on tilted polyacrylamide gels. Our results highlight the need to include local tilt at the probe-sample contact to ensure accurate AFM measurements. This represents a step forward in our understanding of the elastic properties at the surface of soft materials in the broadest sense.

A ply-level based modeling strategy for predicting the delamination behavior of laminated composites under pure and mixed mode loading conditions is implemented within the framework of the Finite Element Method. Each ply and each interface of the laminate is explicitly modeled, with the plies represented by various element types such as conventional shell, continuum shell, and continuum elements, and the interfaces are discretized using cohesive zone elements. The comparison between all models is examined in terms of delamination onset and growth including load-displacement curves, delamination area, computation time, and mode-mixity. The results show that all ply-level based modeling strategies exhibit very good agreement with the analytical results. Moreover, ply-level approach based on shell elements in combination with finite thickness cohesive zone elements offers a numerically efficient simulation tool to predict delamination behavior in laminates.

This paper presents a comprehensive finite element analysis (FEA) of pre-stressed Ultra High-Performance Concrete (UHPC) girders, showcasing intricate structural behaviors under various loading conditions. Utilizing advanced finite element modeling techniques, the study accurately simulates the flexural response of UHPC girders, integrating experimental results from large-scale laboratory tests conducted by researchers at the Turner-Fairbank Highway Research Center. This paper shows the effectiveness of simulating pre-stressing forces via initial equivalent temperature load with relatively accurate stress and strain predictions. The paper also delves into the moment–deflection relationships at critical stages, such as first concrete crack appearance, yielding, and strain localization, to capture the non-linear behavior of UHPC girders under pre-stressed conditions. Additionally, crack propagations were characterized by investigating the damage in tension (DAMAGET) plots. In summary, the results of the finite element model agree well with the experimental observations. Moreover, this study not only demonstrates the effectiveness of FEA in accurately simulating the complex structural behaviors of UHPC girders but also highlights its broader applicability to the design and analysis of other girder types, offering valuable insights compared to ordinary concrete beams.

Trabecular bone, a porous and spongy kind of bone tissue composed of a lattice of connecting rods and/or plates, is crucial for the transfer of weight in crucial joints including the spine, hip, and knee. It is impacted by a variety of metabolic bone illnesses, such as osteoporosis, which result in bone loss, reduced bone strength, and an elevated risk of bone fracture. To promote osseointegration due to the permeable porous, we suggest, in this study, a new approach to design a femoral permeable porous implant to achieve suitable stiffness, lightweight, and biocompatibility for the bone. Accordingly, data are collected from a digital bio-model to design a femoral implant for mimics segmental bone defect (SBD) with a biocompatible material Ti6Al4V (Ti64). To do this, three lattice structures (LSs) are compared and derived from implicit surface modeling called a triply periodic minimal surface (TPMS) to obtain the LS suitable to create it within the solid inner volume of the tibia implant. Thus, performed the finite element analysis (FEA) method for the enhanced Designs and compare them in terms of stress, deformation, and lightweight. [ABSTRACT FROM AUTHOR]

This study established a finite element model to assess the impact of various transverse strengthening techniques on the Xiuzhen River Bridge, a prestressed concrete box-girder bridge. On-site experiments validated the effectiveness of the finite element model. Five different strengthening techniques, namely, adding steel or concrete diaphragms (ASD or ACD), adding composite truss (ACT), strengthening bridge deck (SBD), and setting transverse prestress (STP), were compared. The results demonstrated a significant reduction in the deflection of the bridge using these techniques. SBD technology exhibited the highest deflection reduction rate at 47.91%, and STP technology achieved a maximum reduction rate of 53.92% in the presence of initial bridge damage. In addition, these techniques notably improved the lateral integrity from the load distribution factor (LDF). However, relying solely on the LDF cannot discern the most effective strengthening method. Therefore, a combined LDF and Kullback–Leibler divergence method was proposed to comprehensively analyse the relative entropy (RE) between different models. The results highlighted that SBD technology significantly reduced the RE of the bridge by 82.94%. In the presence of initial damage, ACT technology demonstrated significant stability in reducing the RE, with a sensitivity of only 10.98%. For newly constructed bridges, SBD technology is notably effective; however, for existing bridges, ACT technology may be a reasonable choice. Additionally, an investigation of failure modes emphasized that all the models exhibit similar failure modes, with initial damage and the implementation of different techniques primarily affecting cracking and ultimate load rather than significantly altering the overall failure mode. [ABSTRACT FROM AUTHOR]

Effective sound absorption is crucial in environments like schools and hospitals. This study evaluates open-pore polyurethane foam and perforated onyx panels, which attenuate noise via distinct mechanisms: porous materials convert sound energy to heat through viscous and thermal losses, while perforated panels use resonant behaviour for energy dissipation. The impact of hole geometries and panel orientations on the sound absorption coefficient and noise reduction coefficient was investigated using COMSOL Multiphysics 6.0 for finite element analysis and ISO 10534-2 compliant impedance tube experiments. Six perforated panel configurations were 3D-printed with varying hole diameters and backed by a 24 mm polyurethane foam layer. Both ‘forward’ and ‘reverse’ configurations were assessed. A tapered hole from 4 mm to 2 mm showed the highest sound absorption across the 100–4000 Hz range, with a noise reduction coefficient of 0.444, excelling in both orientations. Reverse designs generally performed less, underscoring the importance of hole geometry and orientation. Experimental results aligned with FEA simulations, validating the computational model. This study elucidates sound absorption mechanisms of porous and perforated materials, providing a validated framework for material selection in noise-sensitive settings and highlighting 3D-printing’s potential in noise control.

Abstract Objective There is a dearth of comprehensive research on the stability of the spinal biomechanical structure when combining Oblique Lumbar Interbody Fusion (OLIF) with internal fixation methods. Hence, we have devised this experiment to meticulously examine and analyze the biomechanical changes that arise from combining OLIF surgery with different internal fixation techniques in patients diagnosed with degenerative lumbar spondylolisthesis. Methods Seven validated finite element models were reconstructed based on computed tomography scan images of the L3-L5 segment. These models included the intact model, a stand-alone (S-A) OLIF model, a lateral screw rod (LSR) OLIF model, a bilateral pedicle screw (BPS) OLIF model, an unilateral pedicle screw (UPS) OLIF model, a bilateral CBT (BCBT) OLIF model, and an unilateral CBT(UCBT) OLIF model. The range of motion (ROM), as well as stress levels in the cage, L4 lower endplate, L5 upper endplate, and fixation constructs were assessed across these different model configurations. Results S-A model had the highest average ROM of six motion modes, followed by LSR, UPS, UCBT, BPS and BCBT. The BCBT model had a relatively lower cage stress than the others. The maximum peak von Mises stress of the fixation constructs was found in the LSR model. The maximum peak von Mises stress of L4 lower endplate was found in the S-A model. The peak von Mises stress on the L4 lower endplate of the rest surgical models showed no significant difference. The maximum peak von Mises stress of the L5 upper endplate was found in the S-A model. The minimum peak von Mises stress of the L5 upper endplate was found in the BCBT model. No significant difference was found for the peak von Mises stress of the L5 upper endplate among LSR, BPS, UPS and UCBT models. Conclusion Among the six different fixation techniques, BCBT exhibited superior biomechanical stability and minimal stress on the cage-endplate interface. It was followed by BPS, UCBT, UPS, and LSR in terms of effectiveness. Conversely, S-A OLIF demonstrated the least stability and resulted in increased stress on both the cage and endplates. Combining OLIF with BCBT fixation technique enhanced biomechanical stability compared to BPS and presented as a less invasive alternative treatment for patients with degenerative lumbar spondylolisthesis.

Abstract The seismic behavior of steel reinforced ultra-high strength concrete (SRUHSC) composite frame was investigated through finite element analysis (FEA) modeling. A FEA model for the seismic analysis of the SRUHSC frame was first established and verified with test results. The numerical model was subsequently used to study the seismic performance of the SRUHSC frame, including the P-Δ skeleton curves, the stiffness degradation, the failure mode, the subsequence mechanisms of plastic hinges and the stress–strain distribution. Finally, a parametric study was carried out to investigate the effect of salient parameters on the behavior of the SRUHSC frame. It was found that with the increment of the concrete strength, yield strength of steel, and linear stiffness ratio of beam to column, the horizontal load-bearing capacity and the elastic stiffness of the structure were improved, but there was no significant effect on the ductility. With the increment of the volume stirrup ratio and structural steel ratio, the horizontal load-bearing capacity and the ductility of the structure were both improved. However, with the increment of the axial-load ratio, there was no obvious change in the elastic stiffness of the structure, but the horizontal load bearing capacity and the ductility of the structure decreased obviously. In addition, the accuracy of a concrete constitutive model in the different degrees of constraint for the SRUHSC frame proposed by the authors was verified with the FEA model.

The microstructure and uniformity of Cu metallization in the through glass via (TGV) structure were investigated through electron backscatter diffraction (EBSD) analysis system and finite element analysis (FEA) method. Two different direct current (DC) electroplating methods were employed for the TGV metallization, including single- and multiple-step electroplating methods. We found that the multiple-step electroplating process with appropriate current density (j)/plating time (t) can efficiently enhance the throwing power (TP) value (uniformity) of electroplated Cu in the TGV metallization. Moreover, the Cu electrodeposition via the multiple-step electroplating process possessed larger grain sizes and high fraction of high angle grain boundaries (HAGBs), including twin boundaries (TBs), which are very beneficial to the mechanical and electrical properties of Cu interconnects. Detailed analyses of the uniformity (i.e., TP), crystallographic microstructure (e.g., grain size), and mechanical characteristics (e.g., ductility) of electroplated Cu derived from single- and multiple-step electroplating process were discussed in this paper.

The ankle joint is pivotal in prosthetic feet, especially in Energy-Storing-and-Releasing feet, favoured by individuals with moderate to high mobility (K3/K4) due to their energy efficiency and simple construction. ESR feet, mainly designed for sagittal-plane motion, often exhibit high stiffness in other planes, leading to difficulties in adapting to varied ground conditions, potentially causing discomfort or pain. This study aims to present a systematic methodology for modifying the ankle joint’s stiffness properties across its three motion planes, tailored to individual user preferences, and to decouple the sagittal-plane behaviour from the frontal and transverse ones. To integrate the multi-axial ankle inside the MyFlex-η, the designing of experiments using finite element analysis was conducted to explore the impact of geometric parameters on the joint’s properties with respect to design constraints and to reach the defined stiffness targets on the three ankle’s motion planes. A prototype of the multi-axial ankle joint was then manufactured and tested under FEA-derived load conditions to validate the final configuration chosen. Composite elastic elements and complementary parts of the MyFlex-η, incorporating the multi-axial ankle joint, were developed, and the prosthesis was biomechanically tested according to lower limb prosthesis ISO standards and guidelines from literature and the American Orthotic and Prosthetic Association (AOPA). Experimental tests showed strong alignment with numerical predictions. Moreover, implementing the multi-axial ankle significantly increased frontal-plane compliance by 414% with respect to the same prosthesis with only one degree of freedom on the sagittal plane without affecting the main plane of locomotion performance.

Highlights This study aims to improve the compressive strength of epoxy at operating temperatures below the glass transition temperature by introducing micron‐sized spherical and milled glass fillers at varying volume fractions. Test specimens were prepared by mixing spherical and milled fillers up to 20% and 15% volume fractions. The room temperature (27°C) results showed that 15% and 10% volume fractions of spherical and milled filler‐reinforced epoxy composites, respectively, exhibited the highest stress‐bearing ability among their respective filler volume fractions and hence were further tested at 45°C and 60°C. 15% spherical and 10% milled fillers enhanced epoxy's yield strength from 103 MPa to 111 MPa and 123 MPa at 27°C and from 67 MPa to 73 MPa and 80 MPa at 60°C. Scanning electron microscopic imaging revealed matrix cracking and filler breakage as the primary failure mechanisms at ambient temperature, while matrix softening at 60°C caused filler‐matrix debonding to dominate. The Three‐Network viscoplastic model was used as matrix property in ABAQUS to simulate the representative volume elements reinforced with milled and spherical fillers at mentioned temperatures. The modulus, yield, and strain softening stresses for both filler‐reinforced epoxy composites are well predicted by the simulations. Simulations revealed that milled fibers endure higher compressive stress than spherical particles at the given temperatures, although matrix stress remains almost the same. Milled fiber epoxy composites exhibit higher yield strength than spherical ones. 10% milled fiber endures the highest strength among all the fillers used. Matrix and filler breakages are witnessed at ambient temperature. Filler‐matrix debonding dominates at elevated temperature. Three‐Network model captures well the milled and spherical epoxy composite's experimental data. [ABSTRACT FROM AUTHOR]

Highlights This paper presents the experimental, analytical, and numerical extensive investigation into the flexural creep performance of pultruded glass fiber reinforced polymer (pGFRP) composites at elevated service temperatures. The experimental phase involved a physical testing program on pGFRP coupons in a four‐point bending setup covering a wide range of loads (12%, 24%, and 37% stress levels) and temperature conditions (20, 40, and 60°C) over a long test duration of 720 h. The analytical Burgers model was employed to provide theoretical insights into the time‐dependent deformation behaviors, while the finite element analysis (FEA) simulations using derived reduction factor validated the accuracy of the proposed procedure. Burgers model was able to capture the experimental data very well and reached the ultimate strain failure limit within about 1.4–50 years depending on the case. The proposed simple FEA procedure yielded a pattern closely resembling the one observed from Burgers model in which they resulted in estimated endurance times with a roughly 15% difference between them. The higher stress and/or temperature, the longer the primary creep stage is. Burgers model is able to capture the experimental data very well in all conditions. Burgers general equation is able to predict failure within about 1.4–50 years. A proposed reduction factor based on Burgers model is utilized in FEA The FEA procedure shows a roughly 15% difference compared to Burgers model. [ABSTRACT FROM AUTHOR]

Objective: There is a dearth of comprehensive research on the stability of the spinal biomechanical structure when combining Oblique Lumbar Interbody Fusion (OLIF) with internal fixation methods. Hence, we have devised this experiment to meticulously examine and analyze the biomechanical changes that arise from combining OLIF surgery with different internal fixation techniques in patients diagnosed with degenerative lumbar spondylolisthesis. Methods: Seven validated finite element models were reconstructed based on computed tomography scan images of the L3-L5 segment. These models included the intact model, a stand-alone (S-A) OLIF model, a lateral screw rod (LSR) OLIF model, a bilateral pedicle screw (BPS) OLIF model, an unilateral pedicle screw (UPS) OLIF model, a bilateral CBT (BCBT) OLIF model, and an unilateral CBT(UCBT) OLIF model. The range of motion (ROM), as well as stress levels in the cage, L4 lower endplate, L5 upper endplate, and fixation constructs were assessed across these different model configurations. Results: S-A model had the highest average ROM of six motion modes, followed by LSR, UPS, UCBT, BPS and BCBT. The BCBT model had a relatively lower cage stress than the others. The maximum peak von Mises stress of the fixation constructs was found in the LSR model. The maximum peak von Mises stress of L4 lower endplate was found in the S-A model. The peak von Mises stress on the L4 lower endplate of the rest surgical models showed no significant difference. The maximum peak von Mises stress of the L5 upper endplate was found in the S-A model. The minimum peak von Mises stress of the L5 upper endplate was found in the BCBT model. No significant difference was found for the peak von Mises stress of the L5 upper endplate among LSR, BPS, UPS and UCBT models. Conclusion: Among the six different fixation techniques, BCBT exhibited superior biomechanical stability and minimal stress on the cage-endplate interface. It was followed by BPS, UCBT, UPS, and LSR in terms of effectiveness. Conversely, S-A OLIF demonstrated the least stability and resulted in increased stress on both the cage and endplates. Combining OLIF with BCBT fixation technique enhanced biomechanical stability compared to BPS and presented as a less invasive alternative treatment for patients with degenerative lumbar spondylolisthesis. [ABSTRACT FROM AUTHOR]

AbstractFailure analysis and fatigue life prediction are important steps in the design procedure of industrial products to assure the safety and reliability of their components. A model to calculate the heat generation by the hysteresis loss in natural rubber subjected to cyclic loads in a uniaxial direction was introduced and the fatigue life prediction model of the rubber was established based on the theory of continuum damage mechanics (CDM). Dynamic mechanical analysis (DMA) was used to measure the viscoelasticity of the rubber material. The heat generation in the rubber material was calculated using a subroutine with the programming software C++ and the temperature rise in the rubber material was analyzed by a thermal finite element analysis (FEA) method. Then static mechanical FEA models of a rubber mount were established and the strain contours of the rubber mounts at various loads were calculated. The total principal strain was used as the fatigue parameter to predict the fatigue life of the rubber mount. Finally, the fatigue lives of the rubber mounts at various loads were measured on a test rig to validate the accuracy of the prediction method. The test results indicated that the fatigue lives predicted considering the temperature rise agreed better with the test results compared with those not considering the temperature rise and we suggest our fatigue prediction method should be applicable to both rubber and other types of components. [ABSTRACT FROM AUTHOR]

This study investigates the manufacturing, testing, and analysis of ultra-thick laminated polymer matrix composite (PMC) beams with the aim of developing high-performance PMC leaf springs for automotive applications. An innovative aspect of this study is the integration of Fiber Bragg Grating (FBG) sensors and thermocouples (TCs) to monitor residual strain and exothermic reactions in composite structures during curing and post-curing manufacturing cycles. Additionally, the Calibration Coefficients (CCs) are calculated using Strain Gauge measurement results under static three-point bending tests. A major part of the study focuses on developing a properly correlated Finite Element (FE) model with large deflection (LD) effects using geometrical nonlinear analysis (GNA) to understand the deformation behavior of ultra thick composite beam (ComBeam) samples, advancing the understanding of large deformation behavior and filling critical research gaps in composite materials. This model will help assess the internal strain distribution, which is verified by correlating data from FBG sensors, Strain Gauges (SGs), and FE analysis. In addition, this research focuses on the application of FBG sensors in structural health monitoring (SHM) in fatigue tests under three-point bending with the support of load-deflection sensors: a new approach for composites at this scale. This study revealed that the fatigue performance of ComBeam samples drastically decreased with increasing displacement ranges, even at the same maximum level, underscoring the potential of FBG sensors to enhance SHM capabilities linked to smart maintenance. [ABSTRACT FROM AUTHOR]

This paper describes a new interleaving methodology to improve composite laminates' low velocity impact (LVI) damage resistance. The approach relies on analyzing interlaminar stress in a conventional aircraft laminate to determine the appropriate interleaving strategy. A model was built to identify the larges interlaminar stress, and two interleaving strategies were defined, normal and shear stress. Four thin interleaving veils were used to validate strategies. Non‐ and interleaved laminates were submitted to LVI tests at 13.5, 25 and 40 (J) of energy. Despite interleaved laminates revealed an increase in thickness and resin volume fraction compared to the reference, they were limited to 10% and 7.6% on shear stress interleaved layups. Interleaved laminates also demonstrated an improved external and internal LVI damage resistance, especially when shear stress interleaving strategy was adopted, preventing external damage and mitigating internal damage up to 59%. No correlation between the veil's type and impact damage demonstrates the importance of interleaving strategies over the veil's characteristics. Highlights: Simplified quasi‐static elastic Abaqus model identified the largest in‐plane normal (axial and transversal) and shear interlaminar stresses;Four thin veils were used to validate interleaving strategies adopted;All laminates were produced using the same conditions to minimize process influence on experimental tests;Under low velocity impact (LVI) tests, interleaving laminates in the largest shear stress interlaminar can prevent external damage and mitigate internal damage up to 59%, comparing to the reference;No correlation between the veils and damage demonstrates the relevance of the interleaving strategy over the veil type. [ABSTRACT FROM AUTHOR]

The automotive industry is increasingly focused on reducing vehicle weight, leading to the widespread adoption of composite materials with high strength-to-weight ratios in both aviation and automotive sectors. These materials are gradually replacing traditional options like steel. Leaf springs, one of the oldest and most common suspension components, continue to be widely used in vehicles. This study aims to replace conventional multi-leaf steel springs with mono-composite leaf springs while preserving the same load-carrying capacity and stiffness. Composite materials, such as glass fiber and epoxy resin, provide advantages including higher elastic strain energy storage, superior strength-to-weight ratios, and enhanced corrosion resistance compared to steel. Consequently, the weight of leaf springs can be reduced without sacrificing performance. The steel and mono-composite leaf springs were modeled using Catia software, and their performance was evaluated using ANSYS 15.0 software. [ABSTRACT FROM AUTHOR]

In this study, we used micro-CT-based finite element analysis to investigate the biomechanical effects of radiation on the microstructure and mechanical function of murine lumbar vertebrae. Specifically, we evaluated vertebral microstructure, whole-bone stiffness, and cortical-trabecular load sharing in the L5 vertebral body of mice exposed to ionizing radiation 11 days post exposure (5 Gy total dose; n = 13) and controls (n = 14). Our findings revealed the irradiated group exhibited reduced trabecular bone volume and microstructure (p < 0.001) compared to controls, while cortical bone volume remained unchanged (p = 0.91). Axially compressive loads in the irradiated group were diverted from the trabecular centrum and into the vertebral cortex, as evidenced by a higher cortical load-fraction (p = 0.02) and a higher proportion of cortical tissue at risk of initial failure (p < 0.01). Whole-bone stiffness was lower in the irradiated group compared to the controls, though the difference was small and non-significant (2045 ± 142 vs. 2185 ± 225 vs. N/mm, irradiated vs. control, p = 0.07). Additionally, the structure-function relationship between trabecular bone volume and trabecular load fraction differed between groups (p = 0.03), indicating a less biomechanically efficient trabecular network in the irradiated group. We conclude that radiation can decrease trabecular bone volume and result in a less biomechanically efficient trabecular structure, leading to increased reliance on the vertebral cortex to resist axially compressive loads. These findings offer biomechanical insight into the effects of radiation on structure-function behavior in murine lumbar vertebrae independent of possible tissue-level material effects. [ABSTRACT FROM AUTHOR]

The Finite Element Method (FEM) has emerged as a powerful tool for predicting the behavior of industrial products, including those with complex geometries or uncommon materials. Finite Element Analysis (FEA) is widely used to study structural vibration-related aspects such as stress, displacement, and velocity. Modal analysis, a standard technique for characterizing the vibrational behavior of structures, is essential for identifying resonance frequencies, optimizing component design, and assessing structural integrity. Finite Elements (FE) modal analysis enables engineers to evaluate numerically the modal parameters, whereas model order reduction (MOR) schemes are exploited to achieve a balance between computational efficiency and accuracy, enabling a more efficient solution for computing transient dynamic analysis. Assessing the accuracy and reliability of FE solutions is a crucial aspect of the design cycle, and model-updating procedures are commonly employed to maximize the correlation between measured and predicted dynamic behavior. This study investigated the accuracy and computational efficiency of linear, quadratic, and cubic hexahedral FE formulations for modal analysis and transient dynamic solutions. More specifically, the documented results demonstrate the profitable use of the eigenenergy norm obtained in eigen solutions as a valid predictor of the accuracy reported using either the time response assurance criterion (TRAC) or the frequency response assurance criterion (FRAC), measured in transient dynamic cases. Moreover, our results also highlight the superior computational efficiency of higher-order formulations for both the eigen and transient dynamic solutions. [ABSTRACT FROM AUTHOR]

This article investigates the influence of process and geometric parameters on deformation during mild steel Submerged arc welding (SAW). This article focuses on optimizing welding process parameters to reduce distortion and improve product quality. The intent of this study is to investigate the effects of technical and geometrical parameters on deformation during submerged arc welding of mild steel using ANSYS and experimental values employing element type brick 8 node 70. The temperature distribution was analyzed using the double ellipsoidal heat source model developed by Goldak, and the amount of deformation was predicted by changing the plate thickness, welding speed and current. The finite element method (FEM) was used to simulate the welding process and obtain an approximate solution. ANSYS software was used for modeling and analysis. The effect of four main parameters of the series (A, B, C, D) on the distortion was analyzed. The simulation results were compared with the experimental values. The study revealed that the maximum distortion determined for SET A was 1.341 mm, corresponding to the experimental value of 1.20 mm. SET B resulted in a maximum distortion of 0.88 mm, corresponding to an experimental value of 0.60 mm. The increase in heat-input in SET C increased the strain/distortion from 1.341 to 2.989 mm, which closely matches the experimental value of 2.60 mm. Increasing the welding speed for SET D reduces the deformation from 2.989 to 2.230 mm, in good agreement with the experimental value of 2.012 mm. SET E investigated the effect of different plate thicknesses on deformation, and the thicker the plate, the lower the maximum deformation. This research can aid in the optimization of welding process parameters and the reduction of distortion in the finished product by forecasting the maximum distortion by varying these parameters. The novelty of this study lies in its investigation of the influence of various variables on the welding process and the distortion that results, which has the potential to significantly enhance the welding process and the caliber of the final product. The findings of this study can be applied in the shipbuilding and automotive industries. [ABSTRACT FROM AUTHOR]

The ankle joint is pivotal in prosthetic feet, especially in Energy-Storing-and-Releasing feet, favoured by individuals with moderate to high mobility (K3/K4) due to their energy efficiency and simple construction. ESR feet, mainly designed for sagittal-plane motion, often exhibit high stiffness in other planes, leading to difficulties in adapting to varied ground conditions, potentially causing discomfort or pain. This study aims to present a systematic methodology for modifying the ankle joint's stiffness properties across its three motion planes, tailored to individual user preferences, and to decouple the sagittal-plane behaviour from the frontal and transverse ones. To integrate the multi-axial ankle inside the MyFlex-η, the designing of experiments using finite element analysis was conducted to explore the impact of geometric parameters on the joint's properties with respect to design constraints and to reach the defined stiffness targets on the three ankle's motion planes. A prototype of the multi-axial ankle joint was then manufactured and tested under FEA-derived load conditions to validate the final configuration chosen. Composite elastic elements and complementary parts of the MyFlex-η, incorporating the multi-axial ankle joint, were developed, and the prosthesis was biomechanically tested according to lower limb prosthesis ISO standards and guidelines from literature and the American Orthotic and Prosthetic Association (AOPA). Experimental tests showed strong alignment with numerical predictions. Moreover, implementing the multi-axial ankle significantly increased frontal-plane compliance by 414% with respect to the same prosthesis with only one degree of freedom on the sagittal plane without affecting the main plane of locomotion performance. [ABSTRACT FROM AUTHOR]