Formulation of the pextension finite elements for the solution of normal contact problems

This work deals with normal contact problems. After a wide literature review, we look for the possibility of achieving a high-precision solution using the principle of minimum potential energy and the Hellinger-Reissner variational principle with penalty and augmented Lagrangian techniques. By positioning of the border of the contact elements, the whole surfaces of the eligible elements fall in contact or in gap regions. This reduces the error of the singularity in the border of the contact domain. Computations with $h$-, $p$- and $rp$-versions are performed. For the $rp$-version, the pre-fixed number of finite elements are moved so that small elements are placed in one or two element layers at the ends of the contact zone. A number of diagrams and tables showing the convergence of the solution (by increasing the number of polynomial degrees p) demonstrate the high efficiency of the proposed solution procedure.