Anisotropic Nonconforming Finite Element Approximation to Variational Inequality Problems with Displacement Obstacle

Studied in this paper is the nonconforming finite element approximation to the second order variational obstacle problem with displacement obstacle on the anisotropic meshess.The optimal error estimates which are the same as those for regular finite element methods are obtained by utilizing some novel techniques and approaches.The application of finite element methods can thus be extended.