A three-dimensional frictional contact element whose stiffness matrix is symmetric

A three-dimensional contact element based on the penalty function method has been developed for contact frictional problems with sticking, sliding, and separation modes in finite element analysis. A major advantage of this contact element is that its stiffness matrix is symmetric, even for frictional contact problems which have extensive sliding. As with other conventional finite elements, such as beam and continuum elements, this new contact element can be added to an existing finite element program without having to modify the main finite element analysis program. One is therefore able to easily implement the element into existing nonlinear finite element analysis codes for static, dynamic, and inelastic analyses. This element, which contains one contact node and four target nodes, can be used to analyze node-to-surface contact problems including those where the contact node slides along one or several target surfaces.