Strain gradient continuum plasticity theories: Theoretical, numerical and experimental investigations

Over the last three decades, a number of researchers have used the gradient-enhanced plasticity theory to model the microstructural material behavior, which is not able to be captured by the conventional plasticity theory, within the continuum based framework. This paper aims to review the strain gradient continuum plasticity in the context of the theoretical, experimental and numerical investigations. A review of the theoretical developments by the several research groups and their applications to the finite element method is presented in this paper. In addition, a review of the various experimental methodologies to study the size effects is presented. Lastly, some open issues in the gradient-enhanced plasticity such as the physical nature of the strain gradients and the physical interpretation of the material length scales are discussed.