Numerical analysis of wave propagation through assemblies of elliptical particles

Wave propagation in granular materials is numerically studied using discrete element simulation. Primary interest is concerned with linking material microstructure with wave propagational behaviors for materials composed of elliptical particles. The discrete element (DEM) scheme uses a nonlinear hysteretic contact law which accounts for differences related to the radius of curvature at the interparticle point of contact. Modeling results yield information on wave speed and amplitude attenuation on two-dimensional, meso-domain model systems of both regular and random assemblies. Particulate models were numerically generated using a biasing scheme whereby partial control of particular fabric measures could be achieved. Three specific fabric measures which were used to characterize the granular material models include branch, contact normal and orienation vectors. DEM simulation results indicated that wave speed and attenuation generally correlated with vector distributions of these fabric variables. A power law relation was proposed between wave speed/attenuation and three averaged projected fabric variables based on orientation, contact normal and branch vectors. Predictions from this specific relation correlated reasonably well with DEM results.