A Nitsche method for the elastoplastic torsion problem

Abstract

This study is concerned with the elastoplastic torsion problem, in dimension n ≥ 1, and in a polytopal, convex or not, domain. In the physically relevant case where the source term is a constant, this problem can be reformulated using the distance function to the boundary. We combine the aforementioned reformulation with a Nitsche-type discretization as in Burman et al. [Comput. Methods Appl. Mech. Eng. 313 (2017) 362–374]. This has two advantages: (1) it leads to optimal error bounds in the natural norm, even for nonconvex domains; (2) it is easy to implement within most of finite element libraries. We establish the well-posedness and convergence properties of the method, and illustrate its behavior with numerical experiments.