A stabilized finite element formulation for finite deformation elastoplasticity in geomechanics

Standard displacement-based finite element formulations have a tendency to lock in the modeling of nearly incompressible materials. This overly stiff response often leads to an overestimation of the collapse load for the system. Employing variational multiscale ideas this paper presents a stabilized/mixed displacement-pressure finite element formulation for finite deformation elastoplastic analysis. The stabilized form is written in the spatial description and is integrated with a smooth surface cap model. Numerical experiments using hexahedral elements with equal low-order interpolations for both displacement and pressure fields show that the new method can successfully remove volumetric locking for the case of near incompressibility in isochoric inelastic flow and also results in stabilizing the pressure field. This formulation can also predict the compaction density induced by the external loads and it is an attractive feature of the method for practical applications in geotechnical/pavement engineering.