Vibro-impact of a plate on rigid obstacles: existence theorem, convergence of a scheme and numerical simulations

The purpose of this paper is to describe a fully discrete approximation and its convergence to the continuum dynamical impact problem for the fourth-order Kirchhoff–Love plate model with nonpenetration Signorini contact condition. We extend to the case of plates the theoretical results of weak convergence due to Y. Dumont and L. Paoli, which was stated for Euler–Bernouilli beams. In particular, this provides an existence result for the solution of this problem. Finally, we discuss the numerical results we obtain

A class of well-posed approximations for constrained second order hyperbolic equations

The purpose of this paper is to present a new family of numerical methods for the approximation of second order hyperbolic partial differential equations submitted to a convex constraint on the solution. The principle is a singular modification of the mass matrix obtained by the mean of different discretizations of the solution and of its time derivative. The major interest of these methods is that the semi-discretized problem is well-posed and energy conserving. Numerical experiments show that this is a crucial property to build stable numerical schemes

Une estimation d'erreur quasi-optimale pour l'approximation par éléments finis du problème de Signorini bidimensionnel

International audienceThe aim of this Note is to present a quasi-optimal a priori error estimate for the linear finite element approximation of the so-called two-dimensional Signorini problem, i.e. the equilibrium of a plane linearly elastic body in contact with a rigid foundation. Previous works on that subject give either non-optimal estimates or with a more restrictive supplementary condition on the solution.On présente dans cette Note une estimation optimale de l'erreur d'approximation par éléments finis affines du problème de Signorini, c'est à dire du problème de l'équilibre d'un corps élastique en contact avec une fondation rigide. Les travaux précédents sur ce sujet donnent soit des résultats non optimaux, soit avec des conditions supplémentaires plus contraignantes sur la solution

Numerical analysis of a one-dimensional elastodynamic model of dry friction and unilateral contact

International audienceThis paper deals with a numerical analysis of a one-dimensional dynamic purely elastic (i.e. hyperbolic) model with dry friction. Since we consider a Coulomb friction law with a slip velocity dependent coefficient, generally, the problem has more than one solution. A mass perturbation approach is developed to regain the uniqueness and to perform the numerical analysis. This study can be viewed as a first step in the numerical analysis of more elaborated dynamic purely elastic problems with dry friction

A uniqueness criterion for the Signorini problem with Coulomb friction

International audienceThe purpose of this paper is to study the solutions to the Signorini problem with Coulomb friction (the so-called Coulomb problem). Some optimal a priori estimates are given, and a uniqueness criterion is exhibited. Recently, nonuniqueness examples have been presented in the continuous framework. It is proved, here, that if a solution satisfies a certain hypothesis on the tangential displacement and if the friction coefficient is small enough, it is the unique solution to the problem. In particular, this result can be useful for the search of multisolutions to the Coulomb problem because it eliminates a lot of uniqueness situations

Fixed point strategies for elastostatic frictional contact problems

International audienceSeveral fixed point strategies and Uzawa algorithms (for classical and augmented Lagrangian formulations) are presented to solve the unilateral contact problem with Coulomb friction. These methods are analyzed, without introducing any regularization, and a theoretical comparison is performed. Thanks to a formalism coming from convex analysis, some new fixed point strategies are presented and compared to known methods. The analysis is first performed on continuous Tresca problem and then on the finite dimensional Coulomb problem derived from an arbitrary finite element method

An unconstrained integral approximation of large sliding frictional contact between deformable solids

International audienceThis paper presents a new integral approximation of frictional contact problems under finite deformations and large sliding. Similar to other augmented Lagrangian based formulations, the proposed method expresses impenetrability, friction and the relevant complementarity conditions as a non-smooth equation, consistently linearized and incorporated in a generalized Newton solution process. However, instead of enforcing the non-smooth complementarity equation in the already discretized system, a corresponding weak formulation in the continuous setting is considered and discretized through a standard Galerkin procedure. Such an integral handling of the contact and friction complementarity conditions, applied previously only to frictional contact problems under small deformations, is extended in the present paper to contact with Coulomb friction between solids undergoing large deformations. In total, the proposed method is relatively simple to implement, while its robustness is illustrated through numerical examples in two and three dimensions

Study of some optimal XFEM type methods

The XFEM method in fracture mechanics is revisited. A first improvement is considered using an enlarged fixed enrichment subdomain aroud the crack tip and a bonding condition for the corresponding degree of freedom. An efficient numerical integration rule is introduced for the nonsmooth enrichment functions. The lack of accuracy due to the transition layer between the enrichment aera and the rest of the domain leads to consider a pointwise matching condition at the boundary of the subdomain. An optimal numerical rate of convergence is then obtained using such a nonconformal method