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This study presents the design and a thorough analysis of a six-bar crank-driven leg mechanism integrated with a skew pantograph, developed for walking robots. The mechanism's dimensions were optimized using a rigorous dimensional synthesis process in GIM software (version 2024). Subsequently, a detailed kinematic analysis was performed in GIM to simulate the leg's motion trajectory, velocity, and acceleration. In parallel, kinematic equations were formulated using the vector loop method, implemented in MATLAB (version R2013-b), and compared with the GIM results for validation, demonstrating the strong agreement between both tools. These results confirm the mechanism's ability to generate a compact, high-lift foot trajectory while maintaining system stability and energy efficiency. An inverse dynamic analysis was carried out to determine the actuator's driving torque, ensuring efficient operation under expected load conditions. Furthermore, topology optimization conducted in SOLIDWORKS (version 2021) significantly reduced the weight of the ground-contacting link while preserving its structural integrity. A subsequent stress analysis validated the mechanical viability of the optimized design, supporting its feasibility for real-world implementation. This research provides a robust foundation for the development of a functional prototype. Its potential applications include mobile robots for sectors such as agriculture and all-terrain vehicles, where efficient, reliable, and adaptive locomotion is crucial. The proposed mechanism strikes an optimal balance between mechanical simplicity, cost-effectiveness, and high performance, making it well-suited for challenging operational environments. [ABSTRACT FROM AUTHOR]

Utilizing non-overlap windings has emerged as a favourable choice for minimizing electrical machine manufacturing costs, among other benefits. Nevertheless, it is widely acknowledged that these windings exhibit a notable level of harmonic contents in the resultant magnetomotive force, which can detrimentally impact machine performance, particularly in terms of torque ripple. In the context of wind energy conversion, maintaining low torque ripple is an essential and demanding prerequisite. Medium-speed wind generators present a good trade-off between high energy yield and low gearbox ratios. So far, medium-speed non-overlap winding wound-rotor synchronous generator (WRSG) technologies have been limited to 10/12 and the less common 16/18 pole/slot combinations. In this study, the analysis of a high-pole number combination (24/27 pole/slots) non-overlap WRSG is carried out to theoretically and comparatively predict the electromagnetic and radial force mechanical stress performance analysis with the 16/18 machine with a phase-shifted non-overlap winding (PSW), at 5 MW power level. The study, which is founded on the finite element analysis (FEA) technique, shows that the 24/27 machine exhibits comparable average torque and torque ripple, lower core losses and significantly reduced radial forces compared to the 16/18 PSW-WRSG. However, the 16/18 PSW-WRSG has a 50% reduction in the radial forces compared to the conventional 16/18 non-overlap winding. Experimental vibration analysis of a 3 kW 16/18 WRSG test machine confirms the radial force and vibration reduction in the phase-shifted winding. [ABSTRACT FROM AUTHOR]

Femoral deformities are highly prevalent in children with cerebral palsy (CP) and can have a severe impact on patients' gait abilities. While the mechanical stress regime within the distal femoral growth plate remains underexplored, understanding it is crucial given bone's adaptive response to mechanical stimuli. We quantified stresses at the distal femoral growth plate to deepen our understanding of the relationship between healthy and pathological gait patterns, internal loading, and femoral growth patterns. This study included three-dimensional motion capture data and magnetic resonance images of 13 typically developing children and twelve participants with cerebral palsy. Employing a multi-scale mechanobiological approach, integrating musculoskeletal simulations and subject-specific finite element analysis, we investigated the orientation of the distal femoral growth plate and the stresses within it. Limbs of participants with CP were grouped depending on their knee flexion kinematics during stance phase as this potentially changes the stresses induced by knee and patellofemoral joint contact forces. Despite similar growth plate orientation across groups, significant differences were observed in the shape and distribution of growth values. Higher growth rates were noted in the anterior compartment in CP limbs with high knee flexion while CP limbs with normal knee flexion showed high similarity to the group of healthy participants. Results indicate that the knee flexion angle during the stance phase is of high relevance for typical bone growth at the distal femur. The evaluated growth rates reveal plausible results, as long-term promoted growth in the anterior compartment leads to anterior bending of the femur which was confirmed for the group with high knee flexion through analyses of the femoral geometry. The framework for these multi-scale simulations has been made accessible on GitHub, empowering peers to conduct similar mechanobiological studies. Advancing our understanding of femoral bone development could ultimately support clinical decision-making. • Distal femoral growth plate stresses quantified with subject-specific simulations. • Large dataset of 50 femurs – 26 healthy, 24 femurs of participants with cerebral palsy. • Knee flexion angle is of high relevance for typical bone growth at the distal femur. • Workflow reveals plausible growth results supported by geometrical analysis. • Multi-scale workflow based on free software published on GitHub. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated student's knowledge and understanding of mechanical stress including strain, and the relation between mechanical stress and strain, using material created by the authors of this text. It also investigated what the students perceived helpful for learning. The material was a complete laboratory setup and was intended to be simple and visual, including a digital part. During the studies in a Swedish upper secondary school, students enrolled in the technology programme took a general introductory course in solid mechanics. The students' participation in our study was composed of four classes. The study was implemented by answering a questionnaire prior to laboratory and a similar one after the laboratory, 85 out of 107 students answered both questionnaires. A thematic analysis was applied on the material, resulting in six thematic groups based on the students' previous knowledge and how much they have learned from the laboratory. To find correlations between the thematic groups, classes, and what the students perceived important for learning, a One-way Analysis of Variance (ANOVA) with multiple comparison post hoc test was performed. A significant difference between the class and the thematic groups was found (p<0.05). Another significant difference was found between the teacher and the class the students were in (p<0.001). This study showed that the teacher was important for the students' perception of solid mechanics during this laboratory and that the interactive lab description played less roll. The teacher's importance depended on what class the students were in. [ABSTRACT FROM AUTHOR]

This paper describes the self-heating effects resulting from mechanical deformation in the additively manufactured aluminium alloy AlSi7Mg0.6. The material's self-heating effect results from irreversible changes in the material's microstructure that are directly coupled with the inelastic deformations. These processes are highly dissipative, which is reflected in the heat generation of the material. To describe such effects, a numerical framework that combines an elasto-viscoplastic Chaboche model with the Gurson Tvergaard Needleman damage approach is analysed and thermomechanically extended. This paper characterises the sample preparation, the experimental set-up, the development of the thermomechanical approach, and the material model. A user material subroutine applies the complete material model for the finite element software Abaqus 2022. To validate the material model and the parameters, a complex tensile test is performed. In order to check the finite element model, the energy transformation ratio is included in the evaluation. The numerical analyses of the mechanical stress evolution and the self-heating behaviour demonstrate good agreement with the experimental test. In addition, the calculation shows the expected behaviour of the void volume fraction that rises from the initial value of 0.0373 % to a higher value under a complex mechanical load. [ABSTRACT FROM AUTHOR]

Electromagnetic forces can lead to the structural failure of power transformers due to extreme loading conditions, vibration, and/or fatigue. Therefore, studying the nature and the magnitude of these forces is a key task in the design and failure analysis of such important equipment. Keeping this issue in mind, this work aims at conducting a numerical analysis in order to evaluate the mechanical stresses and displacements of windings in power transformers due to the action of electromagnetic forces. With this purpose, a finite element model is developed considering electromagnetic and mechanical effects assuming short-circuit conditions. The study compares the cases employing copper and aluminum windings with header tap, in different temperatures. The model developed in this work is verified against analytical solutions. The numerical calculations allow for performing a detailed analysis in terms of the distribution of both displacements and stresses along the windings, which is of great relevance for identifying critical structural points and avoiding structural failure. Overall, the obtained results demonstrate that the finite element model is a useful tool for the structural design of power transformers that allow for investigating and optimizing key aspects before manufacturing. [ABSTRACT FROM AUTHOR]

Failure of soft materials is a fundamental challenge due to the strongly nonlinear and dissipative deformation involved. An experimental and extended finite element study of dynamic crack in silicone rubber are investigated. Hence, material preparation procedures, details of sample as well as testing apparatus which have been used for cutting, pure shear tests are presented. First, the rate of energy restitution and an instantaneous propagation speed were achieved. The crack propagation speed / energy release rate relationships are given for the different strain rates. second, an analysis of the mechanical fields and stress state in the fracture process zone is proposed. Finally, cutting force evolution according to stretches is established. Then, an energybased approach was introduced. Results show that the cutting force and the total cutting energy decreases significantly with increasing deformation rate. [ABSTRACT FROM AUTHOR]

Knee and anterior cruciate ligament (ACL) are among the most injured parts of the body during sports activities. Therefore, this study aimed to evaluate knee torque and mechanical stress on ACL under various conditions of stop-jump landing, as well as identify risk factors for injury, and propose improved strategies. The stop-jump landing was modeled using anthropometric and kinematic data. Knee torque was calculated with the inverse dynamic method, and ACL stress was determined using a Finite Element Model (FEM). Different landing strategies were simulated, including variations in knee flexion at initial foot contact, as well as knee and hip angular displacement. The results showed based on mechanical stress analysis, females (6.30 MPa) had a higher probability of ACL injury compared to males (4.51 MPa). Increasing knee flexion at initial contact caused decreased knee torque and approximately a 7% reduction in ACL stress. Furthermore, increasing knee and hip angular displacement led to a decrease in knee torque, with a reduction in ACL stress by 44% and 11% respectively. To reduce the risk of ACL injury, it is recommended to increase knee flexion at initial contact as well as promote knee and hip angular displacement during landing. [ABSTRACT FROM AUTHOR]

The prediction of spalling failure evolution in the lifespan of aeroengine bearings is crucial for en-suring the safe return of aircrafts after such failures occur. This study examines the spalling failure evolution process in bearings by integrating the proposed spalling region contact stress analysis model with the multi-directional subsurface crack extension analysis model. The results elucidate the general pattern of spalling expansion. Utilizing this methodology, the fatigue spalling fault evolution in bearings is thoroughly analyzed. Additionally, a two-dimensional model has been developed to simulate and analyze crack propagation in the critical direction of the spalling region, significantly enhancing the model's computational efficiency. [ABSTRACT FROM AUTHOR]

Pulsating heat pipes (PHPs) offer significant advantages for the thermal control of electronic components due to their simple manufacturing and high heat transfer rates. The reliability of PHPs has traditionally been assessed through long-life testing, but detailed reliability analyses from an equipment perspective are limited. The study of PHP reliability is essential due to its application and operational conditions. For instance, in aerospace applications these devices operate under severe conditions, and maintenance or replacement is impossible during operation, making them critical components in system functionality. The reliability analysis of PHPs focuses on the manufacturing process, considering future operating conditions. Although preliminary PHP testing will be conducted on Earth, laboratory conditions are less stringent due to the difficulty of replicating launch acceleration and space conditions for long-term testing under microgravity. This study presents an FMECA (Failure Modes, Effects, and Criticality Analysis) of the pulsating heat pipe manufacturing process, breaking down the production of each component. The results indicate that the most critical point is concentrated in the assembly of these components, leading to a higher incidence of welding failures. It recommends further work to improve welding and analyze mechanical stresses within the heat pipe. [ABSTRACT FROM AUTHOR]

Permanent Magnet-Assisted Synchronous Reluctance Machines (PMASynRM) provide a low-cost alternative to Surface PM Machines due to the use of relatively lower grades of rare-earth (RE) or RE-free magnets, as the performance degradation due to weaker magnets is compensated by the presence of reluctance torque. However, the weaker magnets suffer from a high risk of demagnetization, leading to unreliable motor operation. Using a blend of RE and RE-free magnets has the potential to overcome this issue. This paper proposes to blend different grades of various rare-earth (RE) and rare-earth-free (RE-free) magnets in six different combinations and utilizes them in two-layer and three-layer U-shaped PMASynRM topologies with both eight-pole and six-pole variations. The rotor of the various designs is then optimized using a differential evolution (DE) based optimization algorithm to obtain low-cost designs with reduced RE magnet volume and minimum demagnetization risk. The optimization of each design is also integrated with the evaluation of mechanical stresses in the rotor laminations so as to maintain the stresses below the material yield strength. Furthermore, the various performance metrics, such as toque–speed/power–speed characteristics, demagnetization, and efficiency maps, are evaluated for each of the optimized and mechanically feasible designs. A quantitative comparison of the various optimized designs is also obtained to highlight the various trade-offs. The results indicate the feasibility of meeting the baseline torque requirement across the entire speed range, even with a 100% reduction in RE magnet volume and less than 5% demagnetization risk, while achieving a cost reduction exceeding 50%. Moreover, the two-layer, eight-pole designs exhibit relatively higher performance, whereas the three-layer, eight-pole designs are found to be the most economical option. [ABSTRACT FROM AUTHOR]

This study investigates the thermal stress and bolt load distribution in a hybrid panel structure of an aircraft mechanical joint under extreme temperatures. The hybrid panel structure comprises two aluminum alloy splices, six T-shaped composite stringers, and two composite skins, secured together with 96 bolts. This study analyzed the strain induced by thermal stress on composite materials and metals within the structure across temperatures, employing temperature environment tests ranging from room temperature to −54 °C, alongside a carrying capacity test at −54 °C. Furthermore, a three-dimensional simulation model of the panel structure was developed, incorporating considerations for contact, metal elastoplasticity, and the progressive damage failure of composite materials. This model facilitated the determination of thermal stress and bolt load distribution patterns. The results indicate a strong consistency between the finite element analysis outcomes and the experimental data. Temperature variations exacerbate the uneven distribution of bolt loads, concentrating the load near the edges of the hybrid structure while diminishing it in the center. The bolt load distribution parallel to the mechanical load direction forms an "M" shape, with a maximum load magnitude of approximately 31 kN. Perpendicular to the mechanical load, the bolt load undergoes significant changes, especially at the edges, reaching a maximum of about 20 kN, which warrants attention. The bolt-load distribution of the structure with the increase in mechanical load at −54 °C tends to be consistent with that at room temperature. [ABSTRACT FROM AUTHOR]

This study analyzes the Unibridge system, a modular steel box girder employing two pins for longitudinal connections, thereby expediting construction compared to traditional girders. A finite element model was developed to analyze the stress on these pins in a single-box girder with five segments and a reinforced concrete floor slab. Various loads were applied following the Indonesian bridge loading standard, SNI 1725:2016. The model considers operational load analysis and assumes full composite behaviour between the top flanges of the girder and the concrete floor slab. The results indicate that the Von-Mises stress on the pins reaches a maximum of 490.95 MPa under combined service loads, consistently remaining below the specified material yield stress limit of 1200 MPa. Consequently, the Demand Capacity Ratio (DCR) is 0.41. As a result, the Unibridge girder connection pins do not experience plastic deformation under the applied loads. [ABSTRACT FROM AUTHOR]

Boron carbide plays a crucial role in various extreme environment applications, including thermal barrier coatings, aerospace applications, and neutron absorbers, because of its high thermal and chemical stability. In this study, the temperature-dependent elastic stiffness constants, thermal expansion coefficient, Helmholtz free energy, entropy, and heat capacity at a constant volume ( C v ) of rhombohedral B4C have been predicted using a quasi-harmonic approach. A combination of volume-dependent first-principles calculations (density functional theory) and first-principles phonon calculations in the supercell framework has been performed. Good agreement between the elastic constants and structural parameters from static calculations is observed. The calculated thermodynamic properties from phonon calculations show trends that align with the literature. As the temperature rises, the predicted free energy follows a decreasing trend, while entropy and C v follow increasing trends with temperature. Comparisons between the predicted room temperature thermal expansion coefficient (TEC) ( 7.54 × 10 − 6 K−1) and bulk modulus (228 GPa) from the quasi-harmonic approach and literature results from experiments and models are performed, revealing that the calculated TEC and bulk modulus fall within the established range from the limited set of data from the literature (TEC = 5.73–9.50 × 10 − 6 K−1, B = 221–246 GPa). Temperature-dependent C i j s are predicted, enabling stress analysis at elevated temperatures. Overall, the outcomes of this study can be used when performing mechanical and thermal stress analysis (e.g., space shielding applications) and optimizing the design of boron carbide materials for elevated temperature applications. [ABSTRACT FROM AUTHOR]

We have developed Nb-rod method Cu-Nb reinforced Nb3Sn wires (Cu-Nb/Nb3Sn wires), which have significantly improved superconducting characteristics under mechanical stress compared to conventional Nb3Sn wires. Cu-Nb/Nb3Sn wires can be manufactured into coils not only with the conventional wind-and-react (W&R) method but also with the react-and-wind (R&W) method, and the superconducting performance and the mechanical characteristics are both improved by a strain control through pre-bending treatment. Furthermore, elemental technology developments for a higher strength, a higher critical current density, a rectangularization, an enamel coating, a thinner wire for small radius bending, and a stranded wire have made them practical wires with an excellent manufacturability. In the future, Cu-Nb/Nb3Sn wires will be expected to be applied in advanced superconducting equipment such as a high magnetic field NMR/MRI, a particle accelerator, and a large fusion reactor. [ABSTRACT FROM AUTHOR]

In this work, the mechanical behaviour of a thick-walled cylindrical pressure vessel composed of an incompressible isotropic non-linearly hyper-elastic material subjected to internal and/or external pressure is investigated. An analytical solution is proposed for the general form of the free strain energy density and different models including Neo–Hookean, Mooney–Rivlin, and Yeoh are employed. An analysis was conducted to determine the extension ratio at the inner and outer radii as well as the stress distribution, in different cases, namely the application of internal pressure only, external pressure only, and internal and external pressure applied simultaneously. In addition, various pressure values are applied to account for different levels of deformation. In order to strengthen the analytical solution, a finite element model of the pressurised vessel was constructed. A very good agreement has been found between the analytical predictions and the numerical results, suggesting the accuracy of the analytical solution. The analytical solution can be used for parametric studies (material or geometrical parameters) and the design/optimisation of a thick-walled cylindrical pressure vessel subjected to internal and/or external pressure. Additionally, it obviates the requirement for many finite element simulations, where computational cost is an important parameter. [ABSTRACT FROM AUTHOR]

Fibre-reinforced sand (FRS) is a multiphase and multiscale geo-material, which is widely used in geotechnical engineering as supporting structure of excavation of underground space and reinforcement of foundation of underground structures, and its strength is determined by the properties of the heterogeneous substances of the FRS and their coupling mechanical responses. In order to investigate the influence of fibre characteristics and mechanical properties on the shear strength of the FRS, according to the microscopic interface slip effect generated by the interaction between sand particles and the interaction between these particles and fibre, the material phase of the FRS is divided to conceptualize a micro cell element of the FRS that is capable of reflecting the internal material characteristic information of the FRS. Moreover, based on the coordinated deformation condition between fibres and sand particles at the microscale and the couple stress theory that is capable of effectively describing the discontinuous mechanical responses at the sand-fibre interface, a mesomechanism-based multiscale Mohr-Coulomb shear strength criterion of the FRS is derived, and the yield locus of the FRS is also drawn on the p plane. Furthermore, a series of FRS samples with different fibre content and fibre length were prepared by adopting the freezing method, and consolidated and drained triaxial compression tests were conducted on these samples to validate the proposed multiscale coupled Mohr-Coulomb shear strength criterion. Results show that the multiscale coupled Mohr-Coulomb shear strength criterion is capable of effectively reproducing and predicting the yield strength of the FRS. The yield locus of the FRS extends outwards as fibre content and fibre length increase. The yield stress of the FRS predicted by the proposed multiscale coupled Mohr-Coulomb shear strength criterion is in good agreement with that of the test result. [ABSTRACT FROM AUTHOR]

Recent environmental concerns have increased demand for renewable polymers and sustainable green resource usage, such as biomass-derived components and carbon dioxide (CO2). Herein, we present crosslinked polyurethanes (CPUs) fabricated from CO2- and biomass-derived monomers via a facile solvent-free ball milling process. Furan-containing bis(cyclic carbonate)s were synthesized through CO2 fixation and further transformed to tetraols, denoted FCTs, by aminolysis and utilized in CPU synthesis. Highly dispersed polyurethane-based hybrid composites (CPU–Ag) were also manufactured using a similar ball milling process. Due to the malleability of the CPU matrix, enabled by transcarbamoylation (dynamic covalent chemistry), CPU-based composites are expected to present very low interfacial thermal resistance between the heat sink and heat source. The characteristics of the dynamic covalent bond (i.e., urethane exchange reaction) were confirmed by the results of dynamic mechanical thermal analysis and stress relaxation analysis. Importantly, the high thermal conductivity of the CPU-based hybrid material was confirmed using laser flash analysis (up to 51.1 W/m·K). Our mechanochemical approach enables the facile preparation of sustainable polymers and hybrid composites for functional application. [ABSTRACT FROM AUTHOR]

Aiming at the current complex problem of the mechanized high-quality picking of tender tea buds, this paper designs a tender tea bud-picking manipulator. In the picking process, the quality of the petiole and leaf blade of the tender tea bud is crucial, as the traditional cutting picking method destroys the cell structure of the tender tea buds, resulting in rapid oxidation of the cuts, thus losing the bright green appearance and pure taste. For this reason, this paper draws on the quality requirements of tender tea buds and traditional manual picking technology, simulating the process of the manual picking action, putting forward a 'rotary pull-up' clamping and ripping picking method, and designing the corresponding actuating structure. Using PVDF material piezoelectric thin-film sensors to detect the clamping force of the tender tea bud picking, the corresponding sensor hardware circuit is designed. In addition, the finite element analysis method is also used to carry out stress analysis on the mechanical fingers to verify the rationality of the automatic mechanism to ensure the high-quality picking of tender tea buds. In terms of the control of the manipulator, an SMC-PID control method is designed by using MATLAB/Simulink 2021 and Adam 2020 software for joint simulation. The way to control the closed-loop system angle and angular velocity error feedback is by adjusting the PID parameters, which quickly converts the sliding mode control to the sliding mode surface. The simulation results show that the SMC-PID control method proposed in this paper can meet the demand in tender tea bud picking and simultaneously has high control accuracy, response speed, and stability. [ABSTRACT FROM AUTHOR]

In this paper, a sequential Taguchi method for design optimization of an induction motor (IM) for an electric vehicle (EV) is presented. First, a series of empirical and mathematical relationships is systematically applied to reduce the number of possible stator slot rotor bar (SSRB) combinations. Then, the admissible optimal combinations are investigated and compared using finite element (FE) simulation over the NEDC driving cycle, and the three best combinations are selected for further analysis. Each topology is optimized over the driving cycle using the k-means clustering method to calculate the representative working points over the NEDC, US06, WLTP Class 3, and EUDC driving cycles. Then, using the Design of Experiment (DOE)-based Taguchi method, a multi-objective optimization is carried out. Finally, the performance of the optimized machines in terms of robustness against manufacturing tolerances, magnetic flux density distribution, mechanical stress analysis, nominal envelope curve and efficiency map is carried out to select the best stator slot rotor bar combination. It is also found that the K-means clustering method is not completely robust for the design of electric machines for electric vehicle traction motors. The method focuses on regions with high-density working points, and it is possible to miss the compliant with the required envelope curve. [ABSTRACT FROM AUTHOR]

Combined with the general layout of Yaojiaping Hydraulic Project, this paper carries out three dimensional finite element stress analysis and flow field calculation respectively for the diversion system of the main power station with symmetrical Y shape and asymmetric Y shape crescent ribbed steel bifurcation. The calculation results show that the stress distribution at the two sides of symmetrical bifurcation is relatively uniform and the size of the rib is smaller. However, the stress concentration is greater near point A on the inner surface of the main branch taper intersecting line In terms of hydraulics, the head loss of two branches of asymmetric bifurcated pipe is not equal. The straight branch pipe with the main coaxial line has the smallest head loss, and the inclined branch pipe has the largest head loss, but not more than 0.358m of symmetrical bifurcation. It shows that the asymmetric bifurcation is slightly better than the symmetrical Y-shaped bifurcation in terms of head loss and flow pattern of the bifurcation. Considering the structural and hydraulic characteristics of bifurcation as well as the engineering topography, it is suggested that the asymmetric Y-shaped bifurcation layout should be chosen for the diversion system of the main power station in Yaojiaping Hydropower Project. [ABSTRACT FROM AUTHOR]

The development of reliable miniaturized devices capable of performing sensing, actuation, and computing functions in a robust manner strongly depends on the mechanical performance of arrays of micromachines subjected to alternating stresses during operation. Consequently, to enhance the functionality and longevity of these micromachines, it is essential to accurately determine the structural behavior under both static and dynamic loadings. However, this requires knowledge of the stress distribution and variation due to texture anisotropy effects in critical micromachine regions and insight into the material behavior at micrometer length scales. Accordingly, the objective of this study was to develop an effective computational mechanics framework for performing stress analysis of micromachines at resonance. Dynamic finite element analysis of resonating micromachines was performed to elucidate the effect of material damping on the dynamic response. A Poisson–Voronoi diagram was incorporated in the critical region of finite element models of polysilicon micromachines to mimic the local inhomogeneity and anisotropy of the polycrystalline microstructure. A computationally effective static finite element analysis of the steady-state resonant response, validated by the results of the dynamic analysis, was used to obtain the steady-state stress distribution in the critical region of polysilicon micromachines with different textures. Moreover, a probabilistic stress analysis of hundreds of simulations was carried out to examine the stochastic nature of the grain geometry, size, and orientation and the beam width on the maximum equivalent von Mises stress in the critical micromachine region. The present study provides an efficient computational methodology, which integrates local texture into continuum mechanics modeling, for performing stress analysis of dynamic microdevices exhibiting different polycrystalline microstructures. [ABSTRACT FROM AUTHOR]

Orthotropic rectangular plates, featuring central cutouts and subjected to in-plane loading, are extensively employed across various engineering fields, including mechanical, automobile, aerospace, and marine. The introduction of a cutout inevitably leads to stress concentration within the plate. Incorporating carbon nanotubes (CNTs) into the polymer matrix composite has been noted to induce significant heterogeneity in stress fields. Functioning as bridges between the fibers and the matrix, CNTs can effectively mitigate stress concentration and enhance the damage tolerance of the composite. However, accurately determining stress concentration in CNT-based composites requires comprehensive understanding of the geometric discontinuity edge and well-defined evaluation techniques. Among these, the finite element method emerges as a straightforward yet precise approach for studying stress concentration around geometric discontinuities. The present work harnesses the finite element method to investigate stress concentration in CNT-based multiscale composite plates (Glass Fiber/CNT/Epoxy) with central cutouts under static in-plane loading. To validate the model, the derived results are compared with analytical data from conventional composite materials. Moreover, the impact of cutout size on stress concentration is examined for three distinct configurations: plates with a central circular cutout, plates with an elliptical central cutout (major axis in the longitudinal direction), and plates with an elliptical central cutout (major axis in the transverse direction). Preliminary findings suggest a correlation between increased cutout size and augmented percentage reduction in stress concentration. Notably, the maximum percentage reduction in stress concentration is observed in the case of plates hosting an elliptical cutout at the center with the major axis aligned in the transverse direction. [ABSTRACT FROM AUTHOR]

Energy addition using a hot surface ignition device is required for reliable ignition of aircraft compression ignition engines running on fuel variations and at altitude conditions. Thus, durability of the hot surface ignition device is crucial for application in these engines. Thermomechanical stress is one of the key parameters that determine durability, which requires an accurate prediction of the transient temperature field based on well-defined boundary conditions representing the dynamic and complex fluid flow inside engines. To meet this requirement, the present study focuses on transient thermomechanical stress analysis using a sequentially coupled computational fluid dynamics (CFD)-finite element analysis (FEA) approach to understand transient thermomechanical responses of the hot surface ignition device. A three-dimensional transient reacting flow simulation was conducted first using converge software, the results of which were exported to map thermal and pressure boundary conditions onto a structural finite element mesh. Transient thermomechanical stress analysis was performed sequentially using abaqus software utilizing the mapped boundary conditions. The results such as transient temperature history, resultant thermomechanical stress, displacement, potential failure modes, etc., were critically reviewed, which can provide helpful information for further design improvement. [ABSTRACT FROM AUTHOR]

Metal halide perovskites have the potential to contribute to renewable energy needs as a high efficiency, low-cost alternative for photovoltaics. Initial power conversion efficiencies are superb, but improvements to the operational stability of perovskites are needed to enable extensive deployment. Mechanical stress is an important, but often misunderstood factor impacting chemical degradation and reliability during thermal cycling of perovskites. In this manuscript, we find that a commonly used equation based on the coefficient of thermal expansion (CTE) mismatch between perovskite and substrate fails to accurately predict residual stress following solution-based film formation. For example, despite similar CTEs there is a 60 MPa stress difference between narrow bandgap "SnPb perovskite" Cs0.25FA0.75Sn0.5Pb0.5I3 and "triple cation perovskite" Cs0.05MA0.16FA0.79Pb(I0.83Br0.17)3. A combination of in situ absorbance and substrate curvature measurements are used to demonstrate that partial attachment prior to the anneal can reduce residual stress and explain wide stress variations in perovskites. [ABSTRACT FROM AUTHOR]

This document is a curated compilation of twelve articles that explore the field of Additive Manufacturing (AM), also known as 3D printing. The articles cover a wide range of topics, including design optimization, material innovation, and process improvement. They delve into various applications of AM, such as aerospace, medicine, and construction, as well as research-oriented pursuits in material development and prototyping. The articles highlight the versatility and impact of AM in contemporary and future technological landscapes, offering insights into its evolving trends and potential for innovation. [Extracted from the article]

The emergence of hunting technology in the deep past fundamentally shaped the subsistence strategies of early human populations. Hence knowing when different weapons were first introduced is important for understanding our evolutionary trajectory. The timing of the adoption of long-range weaponry remains heavily debated because preserved organic weapon components are extremely rare in the Paleolithic record and stone points are difficult to attribute reliably to weapon delivery methods without supporting organic evidence. Here, we use a refined use-wear approach to demonstrate that spearthrower was used for launching projectiles armed with tanged flint points at Maisières-Canal (Belgium) 31,000 years ago. The novelty of our approach lies in the combination of impact fracture data with terminal ballistic analysis of the mechanical stress suffered by a stone armature on impact. This stress is distinct for each weapon and visible archaeologically as fracture proportions on assemblage scale. Our reference dataset derives from a sequential experimental program that addressed individually each key parameter affecting fracture formation and successfully reproduced the archaeological fracture signal. The close match between the archaeological sample and the experimental spearthrower set extends the timeline of spearthrower use by over 10,000 years and represents the earliest reliable trace-based evidence for the utilization of long-distance weaponry in prehistoric hunting. [ABSTRACT FROM AUTHOR]

Two- and three-wheeled vehicles account for a significant portion of the automobile market in several countries worldwide. In order to advance the capabilities of these vehicles, the integration of direct-injection (DI) technology is essential, given its potential benefits such as high thermal efficiency and low engine-out emissions. Direct injection in small-bore engines, however, further complicates the challenges involved (of DI technology) like fuel impingement and mixture inhomogeneity inside the engine cylinder, driving the need for an in-depth exploration of in-cylinder processes. Consequently, the necessity arises to develop a small-bore direct-injection spark-ignition (DISI) optical engine that incorporates a transparent cylinder and piston top. In this scenario, these transparent components are required to endure a combination of intricate loads and boundary conditions, hence the potential to result in failures. This work aims to assess numerically the effects of these loads and boundary conditions on the transparent components and optimize their thicknesses. For this purpose, a computer-aided design model of a small-bore DISI optical engine (displacement volume of 200 cm3) is developed. The mechanical and thermal loads are extracted from the experimental data and validated computational fluid dynamics model of the same engine configuration. A coupled temperature-displacement finite element analysis methodology is developed in ABAQUS/CAE, and simulations are performed under both steady and transient conditions. Temperature and combined stress distributions within the transparent cylinder and piston top are obtained and analyzed to find their optimum thicknesses. Knowing thermal gradients, combined stresses and displacements under actual conditions helped design the small optical engine with an improved factor of safety. [ABSTRACT FROM AUTHOR]

Background: This review summarizes uses and new applications for dermatological research of in vitro culture models of human skin explants (HSEs). In the last decade, many innovations have appeared in the literature and an exponential number of studies have been recorded in various fields of application such as process culture engineering, stem cell extractions methodology, or cell-to-cell interaction studies under physiological and pathological conditions, wound-healing, and inflammation. Most studies also concerned pharmacology, cosmetology, and photobiology. However, these topics will not be considered in our review. Summary: A better understanding of the mechanisms driving intercellular relationships, at work in the maintenance of 3D tissue architectures has led to the improvement of cell culture techniques. Many papers have focused on the physiological ways that govern in vitro tissue maintenance of HSEs. The analysis of the necessary mechanical stress, intercellular and cell-matrix interactions, allows the maintenance and prolonged use of HSEs in culture for up to 15 days, regardless of the great variability of study protocols from one laboratory to another and in accordance with the objectives set. Because of their close similarities to fresh skin, HSEs are increasingly used to study skin barrier repair and wound healing physiology. Easy to use in co-culture, this model allows a better understanding of the connections and interactions between the peripheral nervous system, the skin and the immune system. The development of the concept of an integrated neuro-immuno-cutaneous system at work in skin physiology and pathology highlighted by this article represents one of the new technical challenges in the field of in vitro culture of HSE. This review of the literature also reveals the importance of using such models in pathology. As sources of stem cells, HSEs are the basis for the development of new tissue engineering models such as organoids or optical clearing tissues technology. This study identifies the main advances and cross-cutting issues in the use of HSE. [ABSTRACT FROM AUTHOR]

As power densification demands are placing electronic packages under greater reliability risk, the consequences of complementary or interacting stresses in producing failure are becoming increasingly significant. As such, it is important that reliability methods and package designs consider how multiplestress interactions may impact product life. Here, the coordination between a novel accelerated testing method and electronic design automation efforts has demonstrated a successful optimization approach for a wire-bonded 2D module layout combining failure mechanisms of electromigration and mechanical stressing. Utilizing custom, physics-of-failure approaches in accelerated testing, interactions can be observed in failure acceleration, which then can be incorporated into design for reliability (DfR) optimization tools. The PowerSynth 2 platform has been utilized as a DfR tool to perform a rapid reliability evaluation incorporating multistress scenarios. This work demonstrates the value added to reliability evaluation techniques when accounting for interacting failure mechanisms and suggests that next-generation power devices consider these effects in lifetime estimation. [ABSTRACT FROM AUTHOR]

Objective: Basilar artery occlusion (BAO) is an infrequent form of acute life-threatening stroke and may occur secondary to vertebral artery dissection (VAD). VAD, which occurs spontaneously and sometimes results from mechanical stress or blunt force trauma to the neck, sometimes occurs in the V1-V2 junction, but there are not many reported cases of those. Herein, we report a pictorially illustrative and clinically informative case of VAD in the V1-V2 junction following BAO. Case Presentation: The patient was a 27-year-old woman who was transferred to our hospital with abrupt severe unconsciousness. On admission, she presented with generalized convulsions and respiratory arrest, and pan-scan CT and CTA indicated BAO. We performed mechanical thrombectomy and achieved recanalization of the basilar artery, and she was diagnosed with BAO secondary to the right VAD at the entry of the C6 transverse foramen (V1-V2 junction). In hindsight, she had scapula and back pain before the onset. She recovered with a modified Rankin scale score of 3 after 90 days from the onset. Conclusion: VAD sometimes occurs at its entry into the transverse foramen of the C6 vertebra. In this case, VAD may be affected by minor trauma and potentially histological fragility due to the embryonic development process. Although BAO is sometimes difficult to diagnose because it presents with various symptoms, BAO secondary to VAD should be considered in cases of abrupt severe unconsciousness preceded by neck, scapula, or back pain in young and healthy persons. [ABSTRACT FROM AUTHOR]

In this paper, the two‐dimensional (2D) (0°/90°) plain‐woven Amosic‐3 SiC/SiC turbine guide vane (TGV) was fabricated using the chemical vapor infiltration method. Thermal and stress analysis of the TGV was conducted using the finite element method analysis. Multiple thermal shock tests at T = 1250, 1350, 1400, 1420, 1450, 1470, and 1480°C were conducted for N = 100, 100, 400, 300, 200, 200, and 700 cycles. After thermal shock tests, the surface damage of the TGV was observed visually, and the micro damage mechanism was analyzed using the scanning electronic microscopy. Micro X‐ray computed tomography was adopted to characterize the internal damages in the SiC/SiC guide vanes. The delamination occurred at the positions approaching internal hollow, due to the weak binding force along the thickness direction and the high thermal shock stress caused by the temperature change. The diameter, area, volume, and sphericity distributions of the pores inside of the guide vanes were also obtained. [ABSTRACT FROM AUTHOR]

Introduction : Dental implants are widely used to replace missing teeth. The crown -to -implant ratio is a determinant factor for the survival/success of dental implants. The aim of this study was to investigate the effect of diameter, length, and crown -to -implant ratio on the stress distribution around dental implants using the finite element analysis (FEA) method . Materials & Methods: In this in vitro study, the cone -beam computed tomography (CBCT) of a patient with an edentulous mandible was used to create a three -dimensional model. The model was uploaded into the Mimics software and the contour model of the mandible was produced. The final file was uploaded into the ABAQUS software for FEA. The mandibular first molar was simulated and reconstructed using six models and in accordance with implant dimensions (diameter: 4.1 and 4.8mm; Length: 6,8,10mm) and axial forces of 200 N and angles of 0°, 15°, 30°, and 45°. The von Mises stress was used to determine the yielding of materials under multifaceted loading from the results of uniaxial tensile tests. Results: The maximum value of von Mises stress, in all six models was observed in the implant, crown, and cortical and cancellous bones, respectively (491.7, 303.5, 205.8,52 MPa). The highest stress value in all models was observed in the implant neck and the stress levels were decreased towards the apical implant. The stress value around the implant increased with increasing crown -to -implant ratio (69.2, 77.6, 92.9 model <1, 1>1 respectively). Conclusion: The stress value around the implant increased with increasing crown -to -implant ratio and inclination angle and decreasing diameter and length. . [ABSTRACT FROM AUTHOR]

Part I of this series of publications addressed the background and fundamentals of the lifetime assessment of prototype Francis turbines. Part II concentrated on the developed methods of numerical calculation and assessment procedures. The present contribution (Part III) deals with the instrumentation and the metrological range of the assessment procedure. The most important sensors, measurement tools, and data acquisition units are presented (background). The instrumentation of the prototype Francis turbine is used, on the one hand, for machine unit monitoring and plant operating and, on the other hand, for generating measurement data to validate and adjust/correct the numerical simulations. Measurement data form the basis for further evaluations at various levels. A wide variety of measured variables are required to carry out the remaining lifetime of a component using fatigue analysis. Those variables include pressure and acceleration signals, vibration monitoring, and strain gauge applications for mechanical stress analysis. The available measurement signals are divided into groups based on the developed method. Thus, already-available data from the control room are compared with machine monitoring and temporarily measured data. The correlation of all available data is essential today to determine an exact idea of the occurring flow phenomena and their effects on the mechanical stresses on the component. This interaction of the different data sources and, subsequently, the use of selected quantities for the numerical calculation are part of the newly developed concept for fatigue strength analysis of mechanical components of a turbine unit (methods). The results of this journal article are divided into the discussion of the necessary instrumentation and mounting of the sensors and into the evaluation, presentation, and interpretation of the measurement data. In addition, a fatigue strength assessment is made at the position of the strain gauges. These results serve as a basis for validating the numerical stress calculation. It is worth mentioning that the validation of the numerical results and the discussion of the deviations and error consideration is carried out in Part IV of this publication series (results). This journal article of the series on condition assessment of prototype Francis turbines ends with a discussion of the results and conclusions for further data processing (conclusion). [ABSTRACT FROM AUTHOR]

Purpose: This study aims to explore the potential benefits favoring the adaptation of structural optimization techniques in the additive manufacturing (AM) of medical utilities to meet the repetitive demand for functionally precise customized orthoses. Irregularities encountered during the conventional treatment of tendon injuries can be eschewed using advanced structural simulation in design and innovative splint fabrication using 3D printing. Design/methodology/approach: A customized mallet finger splint designed from 3D scans was subjected to ANSYS topological simulation comprising multi-level weight reduction to retain optimal mass (100%, 90%, 80%, 70% and 60%). A batch of the four typical 3D printing materials was chosen to conduct a comparative mechanical and thermal stress analysis, facilitating the selection of the optimal one for fabricating functionally adaptive splints. Assurance of structural safety was accomplished through the experimental validation of simulation results against the testing data set of ASTM D695 and ASTM D638 Type-1 specimens over a universal testing machine (UTM). Fused deposition modeling (FDM) 3D printing processed the optimized splint fabrication to assist evaluation of weight reduction percentage, fitting aesthetics, appearance, comfort, practicality and ventilation ease at the user end. Findings: AM efficacy can efficiently execute the design complexity involved in the topology optimization (TO) results and introduces rehabilitation practicality into the application. Topologically optimized splint provided with favorable comfort, stiffness and strengthening features, offers ventilation ease and structural stability for customized appliances, with 30.52% lighter weight and 121.37% faster heat dissipation than unoptimized one. Originality/value: The state of art multidisciplinary optimization featured with structural and material optimization attributes can deliberately meet medical necessity for performance-oriented orthotic devices. [ABSTRACT FROM AUTHOR]

Laminated glass composites are composed of two or more layers of glass and a thermoplastic elastomeric interlayer securely glued together in an autoclave at high temperature and pressure. This composite material which significantly enhances the performance of glass before and after breakage, is desirable for various engineering applications. The main elastomeric interlayer comprises Polyvinyl butyral (PVB), SentryGlas (SG), Ethylene-vinyl acetate (EVA), and Thermoplastic Polyethylene (TPU). These interlayer materials have different unique features which offer a variety of performance benefits for engineering purposes. However, the structural response of laminated glass composites' elements and polymeric interlayers is typically prone to structural modifications relative to temperature applications and other environmental actions such as humidity and solar irradiation. This review compares the weathering resistance of the most common interlayers used in laminated glass composites based on available experimental literature findings. The main mechanical and accelerated ageing tests of laminates with different interlayer materials are summarised, giving evidence of the impact of these environmental actions on the viscoelastic and mechanical properties of laminated glass composites plates. This research provides valuable references for predicting the long-term behaviour and risk evaluation of laminated glass composites under diverse ageing conditions. [ABSTRACT FROM AUTHOR]

The extraction of oil from oilseed material by mechanical pressing is carried out in special machines called mechanical presses. The press's primary component sections are the transmission, press bearings, feed area, press chamber, screw, and barrel output. The screw plays a crucial role in a press's operation. A rotating helical body (screw) inside a cylinder-shaped enclosed space produces the pressing force (pressing chamber) in mechanical presses. In this article, we have designed the screw of an oil press to obtain oil from grape seeds. To make the 3D model, we used SolidWorks software, after which we also simulated the model under stress conditions. In the first phase, the behavior of the 3D model will besimulated for the screw with which a small press is equipped, a model most often used in farms for obtaining oil. Later we also simulated a screw model with a larger pitch to observe the differences in behavior between them. In this paper, we show whether the different pitch of the screw press models influences their degree of erosion and fatigue. [ABSTRACT FROM AUTHOR]

The gradual integration of the additive manufacturing into the common practice involves more complex requirements for the used materials. Although the additive manufacturing was mainly used for the rapid-prototyping purposes, with the development of the high-performance thermoplastic materials, the produced components can be applied not only in the laboratory conditions, but also in the real operation. Therefore, it is necessary to consider also the environmental influences that can significantly shorten the component lifetime. This article presents the 3D printing process for the selected thermoplastic polymers and the experimental verification of the strength analysis of the universal sensor holder together with the quantitative and qualitative comparison of their mechanical properties. [ABSTRACT FROM AUTHOR]

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To study the mechanical properties of steel–concrete joints during construction, the Mao Port Bridge in Shanghai is used as a case study. The mechanical properties of the bridge and the joint under the construction conditions were studied based on the site construction monitoring results, the finite element calculation of the entire bridge and the refined model of the joint. The results show that the finite element analysis of the bridge and the stress analysis of the joint during the construction phase agreed with the measured values, the end of block 0# of the main span remained in compression during construction and the compressive stresses varied in a zigzag pattern with the progress of construction. The lifting of the mid-span steel beam is a critical construction condition where the side spans of the girders are stretched upwards by 20.9 mm and the main spans are stretched downwards by 32.3 mm. When the steel beam was lifted, the joint was compressed as a whole. At the joint, the longitudinal stresses in the steel structure gradually decreased from the front bearing plate to the joint face, while the longitudinal stresses in the concrete structure gradually increased. [ABSTRACT FROM AUTHOR]

The existing research on pavement mechanics was rarely conducted from the perspective of the spatial stress state. In this research, by utilizing analytical solutions, a three-dimensional space calculation program for asphalt pavement was developed to study the spatial distributions of the stress state and damage risk of the pavement structure. First, this study selected various types of pavement structures to analyze the spatial distribution of the stress state. The results indicated that the important influence factors are the order and quantity of asphalt-bound material, chemically stabilized material, and granular material in the structure. In contrast, the thicknesses of these materials have a limited effect. Then, the stress states of the asphalt pavements in winter and summer were compared. The results demonstrated that the tensile region bulges upward at low temperatures, and the structure is more inclined to experience tension and compression simultaneously. In addition, the failure criterion suitable for asphalt mixture materials was applied, and a strength conversion coefficient between different temperatures was proposed to calculate the damage situations of asphalt mixture layers. Three-dimensional images were generated to display the differences in the dangerous positions and damage forms for different structural types and temperature conditions. [ABSTRACT FROM AUTHOR]

The gradual integration of the additive manufacturing into the common practice involves more complex requirements for the used materials. Although the additive manufacturing was mainly used for the rapid-prototyping purposes, with the development of the high-performance thermoplastic materials, the produced components can be applied not only in the laboratory conditions, but also in the real operation. Therefore, it is necessary to consider also the environmental influences that can significantly shorten the component lifetime. This article presents the 3D printing process for the selected thermoplastic polymers and the experimental verification of the strength analysis of the universal sensor holder together with the quantitative and qualitative comparison of their mechanical properties.