A finite element displacement formulation for gradient elastoplasticity (original) (raw)

We present a gradient elastoplasticity model extending the idea of gradient plasticity, by assuming that the underlying elasticity is of the gradient type as well. The numerical implementation is based entirely on a finite element displacement formulation. The model is developed to regularise the ill-posedness caused by strain-softening material behaviour. The displacement field is the only field needed to be discretised using a ½ continuity element. Mesh insensitivity is demonstrated by modelling localisation of deformation in biaxial tests. It is shown that both the thickness and inclination of the shear-band zone are insensitive to the mesh directionality and refinement. The inclusion of gradient terms allows robust modelling of the post-peak material behaviour leading to localisation of deformation.