Numerical model based on meshless method to simulate FSW

In the present work, a numerical models based on the meshless method “the smoothed particle hydrodynamics (SPH)” is developed to simulate the Friction Stir Welding (FSW). This technique type is well adapted to modeling of mixing zone which is subjected to high strain rate. We limit ourselves to two dimensional problems

Une approche thermomécanique 2D pour la simulation du procédé FSW

L'objectif de notre travail est la modélisation thermomécanique du malaxage d'un matériau viscoplastique observé lors du procédé de soudage par friction et malaxage FSW. Nous proposons un algorithme basé sur le couplage d'une approche sans maillage et une technique implicite d'ordre élevé. Une comparaison des résultats est eectuée dans le cas bidimensionnel avec une approche itérative

Investigation of the effect of temper rolling on the texture evolution and mechanical behavior of IF steels using multiscale simulation

The main objective of this study is to simulate texture and deformation during the temper-rolling process. To this end, a rate-independent crystal plasticity model, based on the self-consistent scale-transition scheme, is adopted to predict texture evolution and deformation heterogeneity during temper-rolling process. For computational efficiency, a decoupled analysis is considered between the polycrystalline plasticity model and the finite element analysis for the temper rolling. The elasto-plastic finite element analysis is first carried out to determine the history of velocity gradient during the numerical simulation of temper rolling. The thus calculated velocity gradient history is subsequently applied to the polycrystalline plasticity model. By following some appropriately selected strain paths (i.e., streamlines) along the rolling process, one can predict the texture evolution of the material at the half thickness of the sheet metal as well as other parameters related to its microstructure. The numerical results obtained by the proposed strategy are compared with experimental data in the case of IF steels.French program “Investment in the future” operated by the National Research Agency (ANR)-11-LABX-0008-01, LabEx DAMAS (LST)

Solving hyperelastic material problems by asymptotic numerical method

International audienc

Simulation of instabilities in thin nanostructures by a perturbation approach

International audienceA new numerical method is proposed to simulate instabilities in thin atomistic structures in quasi-static regime. In contrast with previous approaches based on energy minimization or Newton-Raphson methods, the present technique uses a series expansion of atomistic displacements with respect to a loading path parameter, truncated at high orders. The nonlinear set of equations de ned by minimizing the potential energy of the discrete system with respect to nuclei positions is then transformed into a sequence of linear sets of equations, which can be solved e ciently. The solution can be described along very large loading steps without correction, resulting in a signi cant reduction of matrices to be inverted. Finally, the treatment of limit points and snap-back/snap-through arising when instabilities occur is simpli ed due to a continuous description with respect tothe loading path parameter. The method is applied to the analysis of single carbon atom layers nanostructures like graphene sheets or nanotubes in traction or compression regimes. Accuracy and e ciency of the technique is demonstrated by comparisons with iterative Newton procedures

The Asymptotical Numerical Method (ANM) for solving nonlinear multiscale problems

Séminaire invité, Technische Universiteit, Eindhoven, The Netherlands (3 mars 2010

Matériaux hyperélastique et Méthodes Asymptotique Numérique

National audienceDans cet article, on présente un algorithme numérique basé sur une technique de perturbationappelée Méthode Asymptotique Numérique (MAN) pour résoudre des problèmes non linéaires dans lecadre des matériaux hyperélastiques compressibles et incompressibles. L’efficacité et la précision de laméthode sont examinées en comparant cet algorithme avec la méthode classique de Newton-Raphsonpour des problèmes de structures en présence de grandes déformations hyperélastiques et instabilités

Matériaux hyperélastique et Méthodes Asymptotique Numérique

National audienceDans cet article, on présente un algorithme numérique basé sur une technique de perturbationappelée Méthode Asymptotique Numérique (MAN) pour résoudre des problèmes non linéaires dans lecadre des matériaux hyperélastiques compressibles et incompressibles. L’efficacité et la précision de laméthode sont examinées en comparant cet algorithme avec la méthode classique de Newton-Raphsonpour des problèmes de structures en présence de grandes déformations hyperélastiques et instabilités