Rubber Frictionon Self-Affine Road Tracks

摘要

A basic theoretical concept of rubber friction on rough surfaces is presented that relates the frictional force to th. dissipated energy of the rubber during sliding stochastic excitations on a broad frequency scale. It is shown that this of high relevance for tire traction and allows for a prediction of the likely level of friction of tread compounds on th basis of ~‘iscoelastic data. The impact of both, the frequency dependent loss- and storage modulus on the frictional forci during sliding of tires on rough tracks, is demonstrated quantitatively for different sliding velocities. The effect of thi surface roughness of road tracks is described by three characteristic surface descriptors, i.e., the fractal dimension and th4 correlauion lengths parallel and normal to the surface. These descriptors can be obtained from a fractal analysis of the roa texture via stylus- or laser measurements. In particular, it is shown that the applied model of rubber friction is in agreemen with the classical friction data of Grosch, who found a broad maximum for the friction coefficient with increasing slidini speed. The broadness of the friction maximum is shown to be directiy related to the broadness of the roughness scale of ths surface.