Influence of non-steady state loading on two-dimensional wheel-rail pure rolling contact stresses and deformation

In order to study the relation between wheel-rail corrugation surface and non-steady state loading, a two-dimensional elastic-plastic model of repeated frictionless wheel-rail rolling contact was established, the effects of the fluctuating amplitude coefficient of normal contact pressure on the residual stresses, strains and displacements of rail were analyzed.An advanced cyclic plasticity model developed by Jiang and Sehitoglu was used, material ratchetting effect was considered, non-steady state rolling contact was only considered as the harmonic variation of normal contact pressure, repeated rolling contact was simulated by the multiple translations of varying semielliptical Hertzian pressure distribution across elastic-plastic semi-infinite half space.Analysis result shows that non-steady state normal contact pressure results in a wavy rail surface profile with the same wavelength as the pressure; as rolling time increases, rail residual stress increases, but tends to stabilize, rail residual strain also increases, but ratchetting rate decays; when preassure fluctuating amplitude coefficient increases, rail residual stress in rolling direction below the trough and crest of wavy deformation increase respectively, rail residual stress in axial direction, rail residual shear strain and surface displacement in longitudinal direction below the trough increase respectively, but rail residual stress in axial direction, rail residual shear strain and rail surface displacement in longitudinal direction below the crest decrease respectively, the wave depth increases.