Finite Element Estimation of the Residual Stresses in Roller Straightened Rail

ABSTRACT The purpose of this paper is to develop models to accurately predict the residual stresses due to the roller straightening of railroad rails. Several aspects of residual stress creation in rail due to roller straightening are addressed. The effect of the characteristics of the loads applied by the roller-straightener on the stress profile is examined. In addition, the analysis attempts to discern the relative influence of bending and contact on the residual stresses. The last goal is to determine how the heat treatment of rail alters the predicted roller-straightening residual stress field. The loads for the simulation are estimated from available data. To identify the most credible values, a baseline loading case is defined and modeled. These straightening loads are parameterized by considering alternative loading scenarios. Residual stresses and deformations are calculated using these loads. To separate the effects of bending and contact on the residual stress induced by the roller loads, each credible load case is analyzed with two models. One is a 2-dimensional generalized plane strain (GPS) model that accounts only for the flexural stresses. The other is a fully 3-dimensional analysis that includes roll-on-rail contact to make estimates of the true residual stress field. Comparison of the residual stress results from both models reveals the relative influence of local roll-rail contact and bending on the final profile