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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 the reliability-based design optimization (RBDO) model, the mean values of uncertain variables are usually applied as design variables, and the cost is optimized subject to prescribed probabilistic constraints as defined by a nonlinear mathematical programming problem. Therefore, an RBDO solution that reduces the structural weight in non-critical regions provides not only an improved design, but also a higher level of confidence in the design. Solving such nested optimization problems is extremely expensive for large-scale multidisciplinary systems that are likewise computationally intensive. This article focuses on the study of a particular problem representing the failure mode of structural vibration analysis. A new method is proposed, called safest point, that can efficiently give the reliability-based optimum solution under frequency constraints, and then several probability distributions are developed, which are mathematically nonlinear functions, for the proposed method. Finally, the efficiency of the extended approach is demonstrated for probability distributions such as log-normal and uniform distributions, and its applicability to the design of structures undergoing fluid-structure interaction phenomena, especially the design process of aeroelastic structures, is also demonstrated. [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.

أجريت هذه الدراسة بمزرعة الخضر البحثية ومعامل قسم البساتين - كلية الزراعة - جامعة أسيوط - خلال موسمي 2011/2012 ، 2012/2013 وذلك لدراسة تأثير التركيب الوراثي والكثافة النباتية علي محصول الفول الرومي وبالإضافة إلي ذلك أجريت دراسة مبدئية لتقييم القدرة التخزينية للتراكيب الوراثية الجديدة تحت ظروف حرارة الغرفة. وقد اشتملت هذه الدراسة علي ستة تراكيب وراثية جديدة من الفول (رومي3، رومي 5، رومي 12، رومي 13، رومي 80، رومي 101) وثلاثة نظم من الكثافة النباتية (بذرة، بذرتين، ثلاثة بذور في الجورة) ومن الجدير بالذكر أن التراكيب الوراثية الجديدة قد تم استنباطها بواسطة أ.د/ عصمت عبد العظيم والي (رحمه الله) وأ.د/ سيد عباس عبد العال أستاذ الخضر بقسم البساتين ويمكن تلخيص نتائج هذه الدراسة في الآتي: 1-تميز التركيب الوراثي رومي 12 بطول نباتاته ولكنه كان اقل تفريعاً- بينما اتصف التركيب الوراثى رومي 3 بقصر نباتاته وكثرة فروعه. 2-أعطي التركيب الوراثى رومي 5 اعلي إنتاجية لكل من عدد القرون الخضراء/ النبات، ووزن البذور الخضراء/ النبات، والمحصول الكلي من القرون الخضراء للفدان. 3-اختلفت التراكيب الوراثية للفول الرومي فيما بينها من حيث الفقد في الوزن خلال فترات التخزين المختلفة. [ABSTRACT FROM AUTHOR]

In this paper, we are interested particularly in the tube hydroforming process (THP). This process consists of applying an inner pressure combined with an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the load paths can lead to failure. Deterministic approaches are unable to optimize the process by taking into account the uncertainty. So we introduce the reliability-based design optimization (RBDO) to optimize the process under probabilistic constraints to ensure a high reliability level and stability during the manufacturing phase and avoid the occurrence of such plastic instability. Taking some uncertainties into account the process is very stable and associated with a low failure probability. The definition of the objective function and the probabilistic constraints take advantage of the forming limit diagram (FLD) and the forming limit stress diagram (FLSD) used as a failure criterion to detect the occurrence of wrinkling, severe thinning and necking. To validate the proposed approach, the THP is then introduced as an example. The numerical results show the robustness and efficiency of the RBDO to improve thickness distribution and minimize the risk of potential failure modes. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, we consider a mathematical model which describes the dynamic contact between an elastic body and an obstacle. The process is assumed to be dynamic and the contact is modeled with the normal compliance. We present a variational formulation of the problem and prove the existence and the uniqueness of a weak solution. An efficient numerical method is presented to analyze this dynamic contact. This approach exploits the augmented Lagrangian concept and a special time integration algorithm. This is exploited to study the dynamic contact between the rotor and the stator inside an ultrasonic motor SHINSEI USR 60. Numerical results are presented and show the interest of this method to forecast the origin of the principal failure mode of this motor. [Copyright &y& Elsevier]

In topology optimization problems, we are often forced to deal with large-scale numerical problems, so that the domain decomposition method occurs naturally. Consider a typical topology optimization problem, the minimum compliance problem of a linear isotropic elastic continuum structure, in which the constraints are the partial differential equations of linear elasticity. We subdivide the partial differential equations into two subproblems posed on non-overlapping sub-domains. In this paper, we consider the resulting problem as multilevel one and show that it can be written as one level problem [ABSTRACT FROM PUBLISHER]

In this paper, we are interested in the forming of composite part by deep-drawing and laying-up processes. We present a new finite element model for the simulation of these processes. The augmented Lagrangian approach is adopted to treat the frictional contact between the composite fabric and the tools. It is based on a new way of writing the Coulomb's friction law. The numerical simulation is carried out with Abaqus/Explicit software and some numerical results are given to validate the proposed numerical method. [ABSTRACT FROM AUTHOR]

In power electronics applications, embedded mechatronic systems (MSs) must meet the severe operating conditions and high levels of thermomechanical stress. The thermal fatigue of the solder joints remains the main mechanism leading to the rupture and a malfunction of the complete MS. It is the main failure to which the lifetime of embedded MS is often linked. Consequently, robust and inexpensive design optimization is needed to increase the number of life cycles of solder joints. This paper proposes an application of metamodel-assisted evolution strategy (MA-ES) which significantly reduces the computational cost of ES induced by the expensive finite element simulation, which is the objective function in optimization problems. The proposed method aims to couple the Kriging metamodel with the covariance matrix adaptation evolution strategy (CMA-ES). Kriging metamodel is used to replace the finite element simulation in order to overcome the computational cost of fitness function evaluations (finite element model). Kriging is used together with CMA-ES and sequentially updated and its fidelity (quality) is measured according to its ability in ranking of the population through approximate ranking procedure (ARP). The application of this method in the optimization of MS proves its efficiency and ability to avoid the problem of computational cost.

The actual use of computational fluid dynamics (CFD) by aerospace companies is the trade-off result between the perceived costs and benefits. Computational costs are restricted to swamp the design process even if the benefits are widely recognized. The need for fast turnaround, counting the setup time, is also crucial. CFD integrates mathematical relations and algorithms to analyze and solve fluid flow problems. CFD analysis of an airfoil produces results such as the lift and drag forces that determine the performance of an airfoil. Thus, optimizing these aerodynamic performances has proved extremely valuable in practice. The aim of this paper is to model a transonic, compressible and turbulent flow over a NACA 0012 airfoil, using a density based implicit solver, for which a comparison and a validation will be made throught the published experimental data. The numerical results show that the predicted aerodynamic coefficients are in a satisfying agreement with experimental data. Then an aerodynamic shape optimization algorithm, based on a multiobjective algorithm that is an extension of the Backtracking Search Algorithm which was initially developed for single-objective optimization problems only, was used in order to obtain an improved performance control of the aerodynamic coefficients of the optimized airfoil.

In this paper, we present a new method based on Optimal Safety Factors (OSF) in the context of the Reliability-Based Design Optimization (RBDO) analysis of ultrasonic motors with traveling wave taking into account the contact between the different components (stator and rotor). We will underline also the different methods of the RBDO analysis and we highlight the advantage of our approach based on OSF. Numerical results are given to illustrate the proposed method.

In today’s competitive market environment, companies are continuously forced to improve their warehousing operations. To meet high performance goals, tools must be developed to improve efficiency in every aspect of warehousing function. In this paper, we propose a new approach to improve the performance of the warehousing function based on Maturity model, which may better identify, explain, assess and improve this critical function in a supply chain. The aim of this article is to validate the model developed by a case study in a Moroccan company by demonstrating its capacity of assessing the maturity of warehousing function and whether it can develop an improvement roadmap.