Normal and tangential contact problem of surfaces with measured roughness

Experimental results show, that measured creepforce-creep-curves differ in some characteristical points from the analytical one first found by Carter [Proc. R. Soc., Ser. A 112 (1926) 151]. In correspondence to those experiments, the results from calculations with a deterministic two-dimensional contact model prove, that for the rail/wheel contact the initial slope of that curve depends on the characteristics of the effective micro-roughness on the running band, even when dry conditions are considered. Due to the different definition of the real area of contact in the here presented deterministic approach the results look contradictory to the ones from a Greenwood/Tripp-like model [Trans. ASME, Ser. E, J. Appl. Mech. 34 (1967) 153]. Beside the standard roughness parameters of the roughness heights the highest spatial frequencies contained in the roughness pattern have a strong influence on the gradient of the linear region of the creepforce-creep-curve.