Strain localization based on the bifurcation theory: An application to the hypoplastic constitutive model

Many authors have analyzed bifurcation with hypoplasticity, but they have not studied the influence of the hypoplastic parameters on strain localization analysis. The focus of this work is twofold: 1. To analyze the influence of the hypoplastic parameters, which control the strain-softening behavior, on the onset of bifurcation. 2. To study the influence of the mean pressure and the initial voids ratio on the generation of the bifurcation surface on the deviatoric plane and its relation to the limit state surface. Based on these results, it is possible to anticipate whether a shear band is generated in a given loading path. On the one hand, it was found that the more strain-softening the material develops, the earlier the onset of bifurcation in triaxial compression paths. On the other hand, the bifurcation surface is weakly influenced by the initial voids ratio, although this surface is strongly influenced by the confining pressure. Lastly, this work has found the intersection of the bifurcation surface and the limit state surface, and it shows the loading paths in which a shear band is not expected.