A mixed formulation of mortar-based frictionless contact

A class of mortar-based frictionless contact formulations is derived based on a classical three-field mixed variational framework. Within a penalty regularization complemented by Uzawa augmentations, discrete mortar constraints are naturally induced by the variational setting. Major aspects of earlier mortar approaches are obtained through constrained, lumped or unconstrained recovery procedures for the mixed kinematic and kinetic mortar quantities from their projected counterparts. Two- and three-dimensional examples at the infinitesimal and finite deformation regimes highlight the local and global quality of the contact interactions.