Boundary minimum principles for the unilateral contact problems

Abstract

The aim of the present paper is the derivation of boundary variational principles for the unilateral contact problem. Using the inequality constrained principles of minimum potential and complementary energy and the equivalent variational inequality formulations we derive first saddle point formulations for the problems using appropriate Langrangian functions. An elimination technique allows the formulation of two minimum “principles” on the boundary with respect to the unknown normal displacements and reactions of the contact region, respectively. It is also shown that these two minimum problems are equivalent to multivalued boundary integral equations involving symmetric operators. The theory is illustrated by numerical examples solved both by the FEM and the BEM.