Discrete element method (DEM) simulations of planar wave propagation are used to examine the
effect of particle surface roughness on the stiffness and dynamic response of granular materials. A
new contact model that considers particle surface roughness is implemented in the DEM simulations.
Face-centred cubic lattice packings and random configurations are used; uniform spheres are
considered in both cases to isolate fabric and contact model effects from inertia effects. For the range
of values considered here surface roughness caused a significant reduction in stiffness, particularly at
lower confining stresses. The simulations confirm that surface roughness effects can at least partially
explain the value of the exponent in the relationship between stiffness and mean confining stress for
an assembly of spherical particles. Frequency domain analyses showed that the maximum frequency
transmitted through the sample is reduced when surface roughness is considered. The assumption of
homogeneity of stress and contacts in analytical micromechanical models is shown to lead to an
overestimation of stiffness.