In this paper we study a local and a non-local regularization of the system
of nonlinear elastodynamics with a non-convex energy. We show that solutions of
the non-local model converge to those of the local model in a certain regime.
The arguments are based on the relative entropy framework and provide an
example how local and non-local regularizations may compensate for
non-convexity of the energy and enable the use of the relative entropy
stability theory -- even if the energy is not quasi- or poly-convex