Numerical Friction Models Compared to Experiments on Real and Artificial Surfaces

Friction between tire and pavement surface—also referred to as skid resistance in pavement engineering—is a complex phenomenon depending on many influencing parameters like speed, load or wetness of the surface as well as different effects like hysteresis and adhesion. Two different friction model approaches are used in this chapter, a microscale analytical model with special focus on microtexture influence and a multi-scale FE model considering both micro- and macrotexture wavelengths. Both approaches employ a generalized Maxwell model as material formulation for the tire rubber. Real and virtual textures of asphalt surfaces are replicated by 3D SLM printing on stainless steel plates. The virtual texture samples—which are still based on real asphalt surfaces—comprise pure microtextures (without macrotexture elements after filtering) and artificial combinations of sinusoidal waves with two different wavelengths. The printed surfaces are investigated by texture measurements for printing discrepancies with respect to the templates. Friction is measured with a linear friction test rig on these printed samples as well as on a real asphalt surface in dry and wet conditions. The measurements are used for calibration and validation issues by comparing them to the model calculations in wet and dry surface conditions.