Numerical investigations on surface roughness effects in rolling contact of wheels on rails can be done in two principally different ways. On the one hand the data from topography measurements can be used in a deterministic model. Herein the surface heights values are treated as a deviation of the macro geometry. For the consideration of very small asperities in such a model the resolution of the measurements and the grid density in the program has to be very high. On the other hand one can extract statistical data from the surface profiles to use them in a numerical model. Such a stochastical model works independently of the sample length of the surface measurements and the considered deviation wavelengths. The characteristics of the creepforce-creep-curve of the rail/wheel contact with rough surfaces computed for a deterministic model strongly differ from the ones for smooth surfaces. The real area of contact in the rough case is far smaller than the nominal Hertzian contact area and it is the dominant parameter influencing the creepforce-creep-relation. The computation time for the deterministic model is very high for high sample rates needed to model asperities with small wavelengths. Therefore a two-dimensional stochastical model for the normal and tangential contact of rough surfaces is introduced that works very fast. The surface profiles used in the computations with the deterministic model are evaluated in terms of statistical parameters needed in the stochastical model and the results of the two models are compared.
Two-dimensional normal and tangential rail/wheel contact with rough surfaces
Zweidimensionaler normaler und tangentialer Schiene/Rad-Kontakt mit rauhen Oberflächen
2001
12 Seiten, 18 Bilder, 1 Tabelle, 9 Quellen
Conference paper
English
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