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In the mechatronic devices, the finite element analyses are the most used method to determine time-dependent solder joint fatigue response under accelerated temperature cycling conditions, the deterministic analyses are the most used methods. However, the design variables show variability and randomness which will affect the lifetime prediction quality. This paper focuses on solder joint reliability in tape-based chip-scale packages(CSP) with the consideration of uncertainties in material parameters.

This paper presents an experimental/numerical methodology which aims to improve 3D welded tube considering their anisotropic effect, deometrical singularities found in the welded joint, and heat affected zone behaviour by hydroforming process. This process contributes to reduce the number of welding and assembly operations needed to generate complex structures, while improving the weight saving and quality of finished parts. In spite of the advances in the performance of this manufacturing technology, some problems are linked to particularities of certain raw materials and additional studies must be developed, like in the case of welded tubes. The experimental study is dedicated to the identification of stress-strain flow of the base metal and the heat-affected zone from the global measure of tube investigate the heat affected zone mechanical behaviour. Workpiece behaviour's models used to simulate the expansion tests, made it possible to highlight the combined effects of the inhomogeneous behaviour of basic material and heat affected zone, as well as the geometrical singularities found in the welded tubes. From the simulations carried out, it is clear the influence of the plastic flow behaviour of the welded tube in the final results (thickness distribution, stress instability, tube circularity, critical thinning and rupture).

In this study, we utilized the material design library in Ansys Product 2022 R1 to analyze the impact of short plant fibers on the mechanical properties of epoxy resin. We employed the representative volume element (RVE) approach and examined different volume fractions up to 50%. The technique employed in this study was multi-scale modeling based on the finite element method (FEM) for numerical homogenization. Subsequently, we used the same software to develop a five-layer laminated composite. The samples were based on epoxy resin enriched with short plant fibers at fractions of 20% and 30%, as well as pure epoxy resin. The laminated composites were reinforced with carbon fibers. The objective of this study was to analyze the mechanical response of each sample during a tensile test, focusing on multiple parameters. The sought-after results included total deformation, directional deformation, equivalent and elastic stress (Von-mises). The samples containing epoxy resin enriched with 30% of short hemp fibers exhibited remarkable mechanical strength compared to the other samples. These results suggest that the incorporation of short hemp fibers into the matrix led to a significant improvement in the mechanical strength of the composite. [ABSTRACT FROM AUTHOR]

Purpose: The literature abounds with many distinct topology optimisation methods, many of which share common parameter configurations. This study demonstrates that alternative parameter configurations may produce better results than common parameters. Additionally, we try to answer two fundamental questions: identifying the most effective topology optimisation method and determining the optimal parameter selection within this optimisation method. In order to respond to these questions, we conducted a comparative and objective analysis of topology optimisation methods. Design/methodology/approach: This paper evaluates four prominent topology optimisation methodologies, SIMP, RAMP, BESO, and LSM, based on three essential criteria: structural strength, topology quality, and computational cost. We conducted an in-depth examination of 12,500 topology optimisation results spanning a broad range of critical parameter values. These outcomes were generated using MATLAB codes. In the meantime, we comprehensively compared our findings with the existing literature on this subject. Findings: As predicted, our chosen parameters had a substantial effect on the topology quality, structural strength, and computational cost of the topology optimisation outcomes. Across the 12,500 results, many parameter combinations appeared to produce favourable results compared to conventional parameters commonly found in the existing literature. Research limitations/implications: This study focuses exclusively on four specific topology optimisation methods; however, its findings may be extrapolated to apply to other methodologies. Additionally, while it extensively examines the effects of parameters on topology quality, strength, and computational cost, it does not encompass an exploration of these parameters' impacts on other performance criteria. Originality/value: Novel parameter configurations for topology optimisation have been identified, yielding enhanced outcomes in terms of topology quality, structural strength, and computational efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a numerical study on the different parameters that characterize the phenomenon of rupture of thermoplastic materials reinforced with long glass fibers has been made. The material under investigation is polypropylene reinforced with 70% glass fibers (PPGF70), which has been chosen for its mechanical and thermal properties. The effort done in this research is to use the Johnson-Cook failure law as a numerical model to model the failure of this material, with the goal of identifying the damage coefficients Di (i=1,...,5). The methodology used is to simulate the tensile test by comparing the specimen's numerical behavior to the experimental data in order to plot the curves of the strain at failure as a function of triaxiality, taking strain rate, and temperature into consideration. The goal is to find and optimize these factors, so that numerically reproducing the same fractures as in the test is possible. The research reported in this study aims to include this new composite generation into crash simulations for car development. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Several studies demonstrated that a high body mass index (BMI) might actually benefit patients with cardiovascular disease, including coronary heart disease. However, other studies were unable to confirm this paradoxical phenomenon in all populations. Therefore, this study aims to determine the association between BMI and long-term clinical outcomes in ST-segment elevation myocardial infarction (STEMI) patients undergoing percutaneous coronary intervention (PCI). PATIENTS AND METHODS: This was a retrospective cohort study of 400 STEMI patients undergoing PCI. Clinical outcome evaluation was done by face-to-face or phone interview and collecting objective data. Statistical analysis was performed to compare the outcomes between underweight-normal group with overweight- obese group. RESULTS: The incidence of major adverse cardiovascular events (MACE) was lower in patients with higher BMI group in 2-years evaluation (24.1% vs. 39.9%; p < 0.001). Multivariate analysis showed that BMI was an independent predictor of MACE and the incidence of recurrent infarction (OR 2.322 [CI 95% 1.505-3.584; p < 0.001]). The risk of MACE reduces as the weight increases, with a nadir of risk reduction for MACE at 28 to 29.0 kg/m², in which the curve rises after, but remained below the risk associated with BMI of 23 kg/m². CONCLUSIONS: In our population, patients with high BMI have a lower incidence of longterm MACE, especially recurrent myocardial infarction, in patients with STEMI undergoing PCI. [ABSTRACT FROM AUTHOR]

In this paper, we present a new approach to improve the thermo-mechanical performance of the HEMT (high electron mobility transistor) technology. This study aims to solve two optimization problems. The first one is the optimization of the thermal behavior of the HEMT, through the optimization of its maximum operating temperature which influences the electrical characteristics such as electron mobility, and also influences the mechanical behavior of its structure. While the second problem will be the optimization of the mechanical behavior of the same technology, through the optimization of the stresses distribution that also influence the electrical characteristics and reliability of the HEMT structure. The resolution of these two optimization problems will be done, by the multi-objective optimization approach thanks to numerical tools such as Comsol multiphysics and Matlab software, which allows to solve these two problems simultaneously by taking into consideration the imposed constraints. The results obtained have optimized the thermo-mechanical behavior of the HEMT, which proves the efficiency of this approach to solve complex optimization problems.

The complexity challenges of mechatronic systems justify the need of numerical simulation to efficiently assess their reliability. In the case of solder joints in electronic packages, finite element methods (FEM) are commonly used to evaluate their fatigue response under thermal loading. Nevertheless, Experience shows that the prediction quality is always affected by the variability of the design variables. This paper aims to benefit from the statistical power of the R software and the efficiency of the finite element software ANSYS©, to develop a probabilistic approach to predicting the solder joint reliability in Mechatronic Packaging taking into account the uncertainties in material properties. The coupling of the two software proved an effective evaluation of the reliability of the T-CSP using the proposed method.

The electro-thermomechanical modeling study of the High Electron Mobility Transistor (HEMT) has been presented, all the necessary equations are detailed and coupled. This proposed modeling by the finite element method using the Comsol multiphysics software, allowed to study the multiphysics behaviour of the transistor and to observe the different degradations in the structure of the component. Then, an optimization study is necessary to avoid failures in the transistor. In this work, we have used the Covariance Matrix Adaptation-Evolution Strategy (CMA-ES) method to solve the optimization problem, but it requires a very important computing time. Therefore, we proposed the kriging assisted CMA-ES method (KA-CMA-ES), it is an integration of the kriging metamodel in the CMA-ES method, it allows us to solve the problem of optimization and overcome the constraint of calculation time. All these methods are well detailed in this paper. The coupling of the finite element model developed on Comsol Multiphysics and the KA-CMA-ES method on Matlab software, allowed to optimize the multiphysics behaviour of the transistors. We made a comparison between the results of the numerical simulations of the initial state and the optimal state of the component. It was found that the proposed KA-CMA-ES method is efficient in solving optimization problems.