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Fluid-structure interaction (FSI) problems play an important role in many technical applications, for instance, wind turbines, aircraft, injection systems, or pumps. Thus, the optimization of such kind of problems is of high practical importance. Optimization algorithms aim to find the best values for a system's parameters under various conditions. In this paper, we present a new Backtracking Search Optimization Algorithm for multiobjective optimization, named BSAMO, a new evolutionary algorithm (EA) for solving real-valued numerical optimization problems. EAs are popular stochastic search algorithms that are widely used to solve nonlinear, nondifferentiable and complex numerical optimization problems. In order to test the performance of this algorithm, a well known benchmark multiobjective problem has been chosen from the literature, and for FSI optimization, using a partitioned coupling procedure. The method has been tested through a 2D plate and a 3D wing subjected to aerodynamic loads. The obtained Pareto solutions are then presented and compared to those of the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The numerical results demonstrate the efficiency of BSAMO and also its best performance in tackling real-world multiphysics problems. [ABSTRACT FROM AUTHOR]

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 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]

Abstract: In this paper, we are interested in the simulation of prepreg composite deformation by deep-drawing and laying-up. It uses new bi-component finite elements made of woven material in which the nodal interior loads are deduced from fibre tensile strain energy and not polymerized resin membrane energy. Specific treatment is used to analyze the frictional-contact problem between the deformable prepreg composite and the steel rigid tools. The frictional-contact method is based on the Lagrangian formulation and the preconditioned conjugate gradient method. Some numerical tests are given to investigate the performance of the numerical strategies. [Copyright &y& Elsevier]

In this paper, we are interested in the forming of a composite part by deep-drawing and laying-up processes. We present a new bi-component finite element model for the simulation of these processes. The augmented Lagrangian approach is adopted to treat the frictional contact between the composite part and the tools. This augmented Lagrangian treatment is well established for the numerical treatment of metal forming processes [12]. It is based on a new way of writing Coulomb’s friction law. Some numerical results are given to validate the proposed numerical method. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a reliability–mechanical study combination for treating the metal forming process. This combination is based on the augmented Lagrangian method for solving the deterministic case and the response surface method. Our goal is the computation of the failure probability of the frictionless contact problem. Normally, contact problems in mechanics are particularly complex and have to be solved numerically. There are several numerical techniques available for computing the solution. However, some design parameters are uncertain and the deterministic solutions could be unacceptable. Thus, a mechanical contact study is an important subject for reliability analysis: the augmented Lagrangian method coupled with the first order reliability method, and we use the Monte Carlo method to obtain the founding results. The metal forming process is treated numerically to validate the new approach. [Copyright &y& Elsevier]

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]

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 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]