Parametric excitation of wheel/track system and its effects on rail corrugation

In this work the effects on rail corrugation due to the wheel/track parametric excitation is studied by combining wheel/track dynamics, contact mechanics and wear. Firstly, the wheel/track interaction due to the parametric excitation by the varying dynamic stiffness of a discrete track is studied using a low-order time-varying track model in the base of the frequency domain analysis, coupled with a mass wheel. Secondly, the wheel/rail rolling contact mechanics and wear are briefly analyzed according to Hertz theory. Then a quasi-static method is used to simulate rail corrugation formation due to the wheel/track parametric excitation by combining wheel/track dynamics, rolling contact mechanics and wear to form a closed positive feedback loop of corrugation growth. It is found that rail corrugation due to the uneven wear is closely related to the variation pattern of the wheel/rail interaction due to the parametric excitation. Although in practice both initial roughness and parametric excitation take effect, rail corrugation can be developed by the wheel/track parametric excitation alone without initial roughness on the railhead.