1. Introduction#

Two distinct solids are said to be in contact when they share a common surface that is part of their border. Treating one-sided contact is to prevent one of the solids from « crossing » the other. Friction characterizes the tangential sliding of one solid with respect to the other. In Code_Aster, only Coulomb dry rub is available.

The contact in discrete formulation in*Code_Aster* has the following characteristics:

  • The laws of contact and friction are established from quantities that are already discretized: displacements and nodal forces on mesh structures;

  • The touch/friction problem is solved by decoupling it from the structural balance problem.

In this document we will present the various ingredients of the problem:

  • Description of the laws of contact and friction;

Geometric pairing: this is the phase where we link a node to another node or a node to a mesh to create a*potential contact couple, i.e. we identify the degrees of freedom for which we will write discrete relationships of non-penetration;

  • Establishing the touch/friction problem;

  • Description of the algorithms available to solve the touch/friction problem.

This document is therefore limited to the methods known as GCP, CONTRAINTE and PENALISATION.

The so-called « continuous » formulation (FORMULATION =” CONTINUE “in DEFI_CONTACT) is the subject of document [R5.03.52].

The wording associated with elements XFEM (FORMULATION =” XFEM “in DEFI_CONTACT) is discussed in [R5.03.53].

This document also contains theoretical elements to describe the resolution of general unilateral problems (without pairing such as oozing for example) usable by the keyword FORMULATION =” LIAISON_UNIL “.