Constitutive error estimator for the control of contact problems involving friction

In this paper, we propose an error estimator for unilateral contact problems involving friction. The use of a bipotential to formulate the constitutive relation on the contact zone leads to a very straightforward construction of an error in constitutive relation estimator for this kind of problem. Its implementation is described in detail for the case of two elastic bodies and two 2D examples are presented. An error indicator which enables one to estimate the quality of the numerical solution of the non-linear problem is proposed.