Abstract:The states of wheel/rail contact surfaces directly affect the wheel/rail contact stiffness,while the plastic deformation is produced in the wheel/rail surface materials during the rolling contact process of highspeed train,and the ratchet effect is produced caused by the accumulation of wheelrail surface plastic deformation under cyclic contact load.Therefore,the ratchet effect should be considered when studying the normal contact stiffness of the highspeed wheel/rail.A roughness numerical model of highspeed wheel/rail rolling contact was established based on fractal theory of WeierstrassMandelbrot function,and wheel/rail rolling contact microscopic finite element model was constructed by nonlinear finite element software package ABAQUS based on normal contact stiffness theory and considering the ratchet effect of wheel/rail rolling contact.The numerical calculation results show that there may be more accurate analysis of normal contact stiffness by considering the role of plastic deformation of highspeed wheel/rail.Under cyclic contact load,the equivalent plastic strain of rail surface material is increased firstly then trends to be stable with the increase of contact load cycles,and the wheel/rail contact stiffness is decreased firstly then also trends to be stable.Under the same contact load cycles,normal load has obvious influence on wheel/rail contact stiffness,while friction coefficient has less influence on contact stiffness.