Influence of Particle Shape and Surface Friction Variability on Response of Rod-Shaped Particulate Media

Discrete element methods are important tools for the investigation of the mechanics of granular materials. In two dimensions, the reliability of these numerical approaches can be explored using physical tests on rod assemblies. This work highlights the importance of representing the actual distribution of rod shapes and surface friction in numerical simulations. The sensitivity of the response of hexagonally packed rods to minor changes in particle geometry and friction is investigated using a combination of laboratory tests and discrete element simulations. Laboratory test results highlight the influence of small variations in rod geometry on the global response, with the peak friction angle decreasing significantly as the standard deviation of the rod size distribution increased. Small changes in rod shape are also seen to be important. The numerical simulations indicate that the peak friction angle decreases as the standard deviation of the distribution of particle surface friction increases. This paper illustrates the way in which laboratory tests and numerical simulations can be used in a complementary manner to better understand the micromechanics of the response of granular materials.