Constitutive and numerical modeling of mechanical instabilities in granular materials

Many granular materials exhibit mechanical instabilities, customarily referred to as strain softening, when subjected to uniaxial or triaxial compression. This behaviour consists in the loss of the overall strength with increasing deformation, after a peak load level has been reached. Generally this is associated with the formation of narrow bands within the sample where irreversible strains localize.

In the light of continuum mechanics, strain localization has been analysed as a material instability of rate-independent strain-softening plasticity models, leading to a non-uniqueness in the incremental elastoplastic response of a homogeneous body under homogeneous stress and strain fields. Many strategies have been proposed in the literature to model numerically strain-softening and instability phenomena even beyond the onset of localization. Among these, rate-dependent plasticity models have been recognized to provide a satisfactory framework for the analysis of strain localization in solids.

This research project is focused on the constitutive and numerical modelling of the mechanical instabilities related to the strain softening behaviour of frictional materials, with particular emphasis on the modified Cam-Clay model.

Head of project

Dr. Riccardo Conti, SISSA MathLab, riccardo.conti (at)