This paper is devoted to a study of the numerical solution of elliptic hemivariational inequalities with or without convex constraints by the finite element method. For a general family of elliptic hemivariational inequalities that facilitates error analysis for numerical solutions, the solution existence and uniqueness are proved. The Galerkin approximation of the general elliptic hemivariational inequality is shown to converge, and Céa's inequality is derived for error estimation. For various elliptic hemivariational inequalities arising in contact mechanics, we provide error estimates of their numerical solutions, which are of optimal order for the linear finite element method, under appropriate solution regularity assumptions. Numerical examples are reported on using linear elements to solve sample contact problems, and the simulation results are in good agreement with the theoretically predicted linear convergence.

We consider a mathematical model which describes the contact between a linearly elastic body and an obstacle, the so-called foundation. The process is static and the contact is bilateral, i.e., there is no loss of contact. The friction is modeled with a nonmotonone law. The purpose of this work is to provide an error estimate for the Galerkin method as well as to present and compare two numerical methods for solving the resulting nonsmooth and nonconvex frictional contact problem. The first approach is based on the nonconvex proximal bundle method, whereas the second one deals with the approximation of a nonconvex problem by a sequence of nonsmooth convex programming problems. Some numerical experiments are realized to compare the two numerical approaches.Keywords: linearly elastic material, bilateral contact, nonmonotone friction law, hemivariational inequality, finite element method, error estimate, nonconvex proximal bundle method, quasi-augmented Lagrangian method, Newton method.

International audienceWe consider a mathematical model which describes the equilibrium of an elastic body in frictional contact with an obstacle. The contact is modelled with normal compliance and unilateral constraint, associated with a slip-dependent version of Coulomb’s law of dry friction. We present a weak formulation of the problem, then we state and prove an existence and uniqueness result of the solution. The proof is based on arguments of elliptic quasivariational inequalities. We also study the finite element approximations of the problem and derive error estimates. Finally, we provide numerical simulations which illustrate both the behaviour of the solution related to the frictional contact conditions and the convergence order of the error estimates

We consider a mathematical model which describes the frictional contact between a linearly elastic body and an obstacle, the so-called foundation. The process is static and the contact is modeled with normal compliance condition of such a type that the penetration is restricted with unilateral constraint. The friction is modeled with a nonmonotone law in which the friction bound depends both on the tangential displacement and on the value of the penetration. In order to approximate the contact conditions, we consider a regularized problem wherein the contact is modeled by a standard normal compliance condition without finite penetrations. For each problem, we derive a variational formulation and an existence result of the weak solutions of regularized problems is obtained. Next, we prove the convergence of the weak solutions of regularized problems to the weak solution of the initial nonregularized problem. Finally, we provide a numerical validation of this convergence result. To this end we introduce a discrete scheme for the numerical approximation of the frictional contact problems. The solution of the resulting nonsmooth and nonconvex frictional contact problems is found, basing on approximation by a sequence of nonsmooth convex programming problems. Some numerical simulation results are presented in the study of an academic two-dimensional example.