Modeling of elasto-plastic behaviour of granular materials using multi-particle finite element simulations

The method of multi-particle finite element involving assemblies of meshed particles interacting through finite-element contact conditions is adopted to study the plastic flow of a granular material with highly deformable elastic-plastic grains. In particular, it is investigated whether the flow rule postulate applies for such materials. Using a spherical stress probing method, the influence of incremental stress on plastic strain increment vectors was assessed for numerical samples compacted along two different loading paths up to different values of relative density. Results show that the numerical samples studied behave reasonnably well according to an associated flow rule, except in the vicinity of the loading point where the influence of the stress increment proves to be very significant. The influence of relative density and initial loading path is discussed.