Strain-gradient plasticity theory in large strain

This paper presents a large strain finite element formulation based on strain-gradient plasticity theory which is suitable for simulation of strain localization. A local elasto-plastic constitutive relation introduced in the formulation is characterized by the independence from mesh discretization. A mixed formulation with finite element and Lagrange multipliers is adopted, which enables 2D and 3D formulation without any difficulties similar to the ones of the Cl finite elements. 1D model is formulated at first and is fully examined by comparing the analytical solutions with an earlier model with Hermitian elements (Chambon et al. 1998). A 2D model is then formulated straightforwardly and a series of biaxial test are performed to investigate a 2D shear-banding problem.