Mixed finite element methods for unilateral problems: Convergence analysisand numerical studies

In this paper, we propose and study different mixed variational methods in order to approximate with finite elements the unilateral problems arising i n contact mechanics. The discretized unilateral conditions at the candidate contact interface are expressed by using either continuous piecewise linea r or piecewise constant Lagrange multipliers in the saddle-point formulatio n. A priori error estimates are established and several numerical studies c orresponding to the different choices of the discretized unilateral conditi ons are achieved.