A first regularity result for the Armstrong-Frederick cyclic hardening   plasticity model with Cosserat effects
  The purpose of this article is to prove the H\"older continuity up to the boundary of the displacement vector and the microrotation matrix for the quasistatic, rate-independent Armstrong-Frederick cyclic hardening plasticity model with Cosserat effects. This model is of non-monotone and non-associated type. In the case of two space dimensions we use the hole-filling technique of Widman and the Morrey's Dirichlet growth theorem. 
Krzysztof Che{\l}mi\'nski, Patrizio Neff, Sebastian Owczarek
math.AP