Analysis of rolling contact with kinematic hardening for rail steel properties

Abstract

This study presents calculations of two-dimensional rolling contact deformation for rail steel properties. Finite element analyses, previously carried out for perfect plasticity, are extended to the kinematic hardening behavior of rail steel. A three-parameter elastic-linear-kinematic-hardeningplastic description of the cyclic stress-strain behavior of rail steel is inserted in the finite element model. Steady state results are obtained after two translations. The effects of the kinematic hardening at three relative peak pressures p o k k = 4.0, 4.5 and 5.0 are examined. The calculations evaluate the rim distortion, the cyclic plastic strains and the residual stresses, the shakedown limit for kinematic hardening and the effects of strain-amplitudedependent kinematic properties. The calculations reveal that the kinematic hardening of rail steel produces substantial alterations relative to the deformation and residual stresses associated with perfect plasticity. Cyclic strains are an order of magnitude smaller and the residual stresses are about half the value of comparable relative contact pressures. While the relative elastic shakedown limit, p o k k = 4 , is the same as for perfect plasticity, absolute values of wheel load at shakedown are modest because of the relatively low value of the kinematic yield strength of rail steel. Accordingly, a 33000 lbf (146.7 KN) wheel load applied to a new rail produces a relative peak contact pressure p o k k = 6.2 which exceeds the corresponding shakedown limit.