Mixed finite element formulation in large deformation frictional contact   problem
  In this paper, we propose an efficient numerical treatment for solving contact problems with friction between deformable bodies. The discretized normal and tangential constraints at the candidate contact interface are expressed by using either continuous piecewise linear or piecewise constant Lagrange multipliers. Several numerical studies corresponding to this choice are achieved in the PLAST2 code. 
Laurent Baillet (LMCS), Taoufik Sassi (LMNO)