Abstract:A consistent formulation for unilateral contact problems including frictional work hardening or softening is proposed. The approach is based on an augmented Lagrangian approach coupled to an implicit quasi-static Finite Element Method. Analogous to classical work hardening theory in elasto-plasticity, the frictional work is chosen as the internal variable for formulating the evolution of the friction convex. In order to facilitate the implementation of a wide range of phenomenological models, the friction coef… Show more
“…Cet article rassemble un certain nombre de résultats obtenus au cours des dernières années ; chacun d'entre eux ne constitue qu'une réponse partielle, mais pris dans leur ensemble, ils fournissent les raisons de la confiance que nous avons dans cette approche, entretenue par ailleurs par son efficacité sur des problèmes industriels [ 6,17,18,24]. Des techniques multigrilles ou parallèles tout à fait spécifiques sont en cours de développement afin de réduire le temps calcul des algorithmes [7,8].…”
aux systèmes d'équations non différentiables issues de la mécanique du contact. La première partie fournit quelques résultats théoriques pour un problème d'obstacle type. Dans la seconde partie, seule une approche heuristique permet d'appréhender le comportement de l'algorithme de Newton pour des problèmes comportant, outre le contact unilatéral, des non linéarités comme le frottement et l' élasto-plasticité. ABsTRAcr.-This paper is devoted to studying the global convergence of the Newton method generalized to systems of non differentiable equations issued from the contact mechanics. In the first part, sorne theoretical results are presented for a typical obstacle problem. In the second part, the behaviour of the Newton algorithm is analyzed by an heuristic approach. In this way, others non linearities, like friction or elastoplasticity, together with unilateral contact, can be taken up.
“…Cet article rassemble un certain nombre de résultats obtenus au cours des dernières années ; chacun d'entre eux ne constitue qu'une réponse partielle, mais pris dans leur ensemble, ils fournissent les raisons de la confiance que nous avons dans cette approche, entretenue par ailleurs par son efficacité sur des problèmes industriels [ 6,17,18,24]. Des techniques multigrilles ou parallèles tout à fait spécifiques sont en cours de développement afin de réduire le temps calcul des algorithmes [7,8].…”
aux systèmes d'équations non différentiables issues de la mécanique du contact. La première partie fournit quelques résultats théoriques pour un problème d'obstacle type. Dans la seconde partie, seule une approche heuristique permet d'appréhender le comportement de l'algorithme de Newton pour des problèmes comportant, outre le contact unilatéral, des non linéarités comme le frottement et l' élasto-plasticité. ABsTRAcr.-This paper is devoted to studying the global convergence of the Newton method generalized to systems of non differentiable equations issued from the contact mechanics. In the first part, sorne theoretical results are presented for a typical obstacle problem. In the second part, the behaviour of the Newton algorithm is analyzed by an heuristic approach. In this way, others non linearities, like friction or elastoplasticity, together with unilateral contact, can be taken up.
“…The results presented disclose the versatility of the mixed formulation in dealing with global evolutions of the friction coefficient. However, due to the difficulties related with measuring the local variations of the friction coefficient, it is very difficult to correlate effectively the law described with experimental results [121]. The mixed formulation of contact with friction is also applicable to describe anisotropic behaviour of Coulomb's friction coefficient.…”
Section: Frictionmentioning
confidence: 98%
“…In fact, the Coulomb's friction law can be generalised to consider the friction cone evolution according with one or more internal variables. Neglecting the anisotropic component of friction, it is only necessary to change the friction law and the complementary condition to [121]:…”
This paper describes a fully implicit algorithm developed and optimized to simulate sheet metal forming processes. This algorithm was implemented in the inhouse code DD3IMP. Attention is paid to the augmented lagrangian method adopted to treat the contact with friction problem. The global resolution of the coupled equilibrium and contact problem is performed in a single loop, with a static implicit iterative Newton-Raphson scheme. This demands particular attention in the contact search algorithm, which in this case adopts a parametric description of the tools. In order to highlight the adopted strategies a review of the state-of-the-art in sheet metal forming simulation is presented, with respect to models reliability and efficiency.
“…Modelling such a mechanical interaction can be quite complex, and is still a great challenge [32,33,34,35] . In the current study, since the focus is to find an alternative approach to explore the loads as developed along the walls of a hopper during filling, the interaction between the contacting surfaces of the hopper and the stored particulate solids was modelled with a very simplified constitutive model of Coulomb friction [34,35,36]. A constant friction coefficient μ was assumed and implemented in the model.…”
A novel progressive filling approach was adopted in a numerical effort to represent the pilling process of particulate solids. It was implemented in a finite element analysis to investigate the development of loads along the walls of a conical steep hopper during filling. The loads were interpreted as normal pressure and frictional traction. An analysis of the conventional so-called 'switch on' filling was also conducted. Results form both analyses were compared with calculation based on classical theories for the loads acting on the wall of a steep hopper. A good agreement in such comparisons indicates that the progressive filling as adopted is a feasible approach as a finite element analysis to applications where analytical solutions are limited.
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