The necessity to approximate dynamic contact problems arises in many
engineering processes. Because of the local effects in the contact
zone, adaptive techniques are suited to improve the finite element discretisation of such problems.
In this article, the Newmark method in time
and finite elements in space are used to approximate the solution numerically. A spatial error
estimator is derived from the semi-discretised problem. The approach relies on auxiliary problem, which is
a variational equation. An adaptive refinement
process is based on this error control. Numerical results illustrate the performance of the presented
method.