Non-uniqueness of critical solid fraction considering boundary conditions and strain-rate effects

Abstract The critical solid fraction (ϕJ), which marks the transition between and liquid phases in jamming diagram, is influenced by several factors. In this study, dependency of ϕJ on strain rate boundary conditions examined through discrete element method simulations considering a frictionless polydisperse granular system. Different approaches are used to determine ϕJ. observed effect due nonuniform distribution induced clustering particles close rigid-wall boundaries at high compression rates. within sample that periodic-boundary as decreases. With increasing rate, major force transmission network contains fewer mechanically stable less network. This causes assembly lower fraction. These networks, however, fragile disintegrate quickly upon relaxation.