Phase transition in monodisperse granular materials: How to model it by using a strain hardening visco‐elastic‐plastic constitutive relationship

During heating (loading characterised by a progressive increase in strain rate) and cooling decrease numerical tests, performed using Discrete Element codes, granular materials experience phase transition phenomena, named this paper ‘dry liquefaction’ (when from solid the material starts behaving like fluid) resolidification’ (freezing, when fluid solid). The aim of consists reproducing phenomena hardening visco-elastic-plastic model based on critical state concept kinetic theories gases. authors demonstrate that crucial is role isotropic softening/hardening, which describes size elastic domain capability skeleton storing energy according to permanent force chains. main ingredients are: (i) additivity quasi-static collisional stresses, (ii) balance equation governing evolution temperature, interpreted latter as an additional internal variable for system contribution, (iii) mixed kinematic characterising incremental constitutive relationship. has been both calibrated validated Method (DEM) results, obtained testing dry assemblies monodisperse spheres under true triaxial loading conditions.