Analysis of shear band bifurcation with a hypoplastic model for a pressure and density sensitive granular material

The focus of the present paper is to investigate the possibility of shear band bifurcation in rate-independent, cohesionless and dry granular materials based on a hypoplastic constitutive model. The hypoplastic constitutive model is of the rate type and incrementally nonlinear. The current density is included in the constitutive model as a state parameter in addition to the stress tensor. With a unified description of the interaction between pressure level and limit densities the model can be applied to a wider range of pressures and densities. Thus, the influence of density and pressure on the initiation of shear bands can be investigated with the a single set of constitutive constants. For plane strain compressions starting from various initial densities and pressures the predictions of the bifurcation analysis are discussed and compared with earlier investigations. (C) 1999 Elsevier Science Ltd. All rights reserved.