Influence of strain rate on strength and deformation of granular material: A DEM based study

Granular materials are subjected to compressive loading in various scenarios, including ceramic pebble beds in fusion reactors, packed granular beds in chemical reactors, sand beneath structural foundations and dams, ballast in railway tracks, and food grain storage in silos. Granular materials behave differently under varying strain rates, influenced by particle shape, size, friction, cohesion, roughness, elasticity, and coefficient of restitution. This study uses three-dimensional Discrete Element Method (DEM) tool LIGGGHTS to investigate the effect of strain rate, ranging from quasi-static to dynamic loading, in uniaxial compression mode. A progressive replacement breakage criterion is applied to particles that exceed the critical stress during simulation, based on an energy threshold, following Weibull distribution for fragment generation. This study establishes a comprehensive correlation between micro and macro phenomena. Particle-level properties such as contact force, acceleration, particle breakage, rearrangement affect the macro-scale phenomena such as stress-strain response, peak strength, and failure modes. The findings reveal that strain rate variations significantly impact the breakage behavior of particles. This study provides valuable insights into the strain rate dependence of granular material behavior, contributing to a deeper understanding of their mechanical performance under varying loading conditions.