Residual stress and its effect on ratcheting of heavy-haul rails
Yifei Li, Peter Mutton, Cong Qiu, Qianhua Kan, Wenyi Yan
Abstract
• Destructive contour method for measuring residual stress in rails is presented. • Integrating residual stress into FEA model to assess rail ratcheting behaviours. • Tensile residual stress at railhead accelerates the onset of ratcheting damages. • The redistribution of the residual stress occurs in the first loading cycle. Residual stress from manufacturing significantly impacts rail durability under the conditions of repeated wheel-to-rail contact. Using the destructive contour method, this study assessed the manufacturing-introduced residual stress in a low-alloyed heat-treated heavy haul rail by measuring surface displacements due to stress relaxation after making a cut into the rail. A two-dimensional map showing the longitudinal residual stress distribution was constructed and applied to a quasi-static wheel-rail contact finite element model to explore the potential effect of residual stress on ratcheting behaviours of the rail with practical working conditions. Findings revealed that tensile longitudinal residual stress at the railhead, a result of manufacturing, markedly accelerates the onset of damages driven by the ratcheting mechanism, such as rolling contact fatigue cracks. Additionally, the residual stress redistributes after the first loading cycle due to the plastic deformation under the combined contact stresses and residual stress, and then it stabilizes in subsequent cycles. This research validates the utility of the contour method for mapping residual stresses and demonstrates how manufacturing-induced tensile stress detrimentally impacts ratcheting behaviours in heavy-haul rails, thus enhancing comprehension regarding the influence of residual stress on rail degradation.