Numerical implementation of two nonconforming finite element methods for unilateral contact

We consider the finite element approximation of the unilateral contact prob lem between elastic bodies. We are interested in a practical problem which often occurs in finite element computations concerning two independently di scretized bodies in unilateral contact. It follows that the nodes of both b odies located on the contact surface do not fit together. We present two di fferent approaches in order to define unilateral contact on nonmatching mes hes. The first is an extension of the mortar finite element method to varia tional inequalities that defines the contact in a global way. On the contra ry, the second one expresses local node-on-segment contact conditions. In b oth cases, the theoretical approximation properties are given. Then, Ne imp lement and compare the two methods. (C) 2000 Elsevier Science S.A. All righ ts reserved.