Wheel-rail rolling-sliding contact mechanical behavior of high-speed railways based on the impact fatigue constitutive model

Impact fatigue refers to the phenomenon in which materials or structures, subjected to repeated impact loading, experience localized stress concentrations and rapid strain accumulation, leading to the initiation of internal micro-damage and ultimately culminating in fracture failure. Impact fatigue loads are characterized by their brief duration, rapid loading rates, and significantly elevated strain rates, which has greater perniciousness than conventional fatigue. The dynamic contact forces between the wheel and rail of high-speed trains exhibit classic characteristics of impact fatigue loading, which induces the accumulation of impact fatigue damage, accelerates the deterioration of material mechanical properties; and consequently, compromises the operational safety of high-speed trains. In light of this, the present study integrates a material-based impact fatigue damage-coupled constitutive model to develop a comprehensive three-dimensional half-wheel-rail rolling contact finite element model. The stress-strain states and stick-slip characteristics of wheel-rail rolling/sliding contact are clarified, and the distribution features and accumulation evolution law of wheel-rail impact fatigue damage are analyzed. Meanwhile, the effects of train speed, friction coefficient, and traction coefficient on impact fatigue damage are explored, and the influence of material constitutive model on typical wheel-rail contact mechanical behavior is examined. The results clearly indicate that the proposed impact fatigue model is able to well represent the wheel-rail contact responses, stick-slip distribution characteristics and damage accumulation law. Under repeated rolling contact, the impact fatigue damage of the rail exhibits a nonlinear cumulative increasing trend with the rise of rolling cycles; however, the growth rate gradually decreases and eventually tends to stabilize approximately. Compared with the elastoplastic constitutive model, the wheel-rail contact mechanical responses predicted by the impact fatigue constitutive model are more severe and dangerous. Moreover, such coupling effect gradually intensifies with the increase of rolling cycles. These findings provide valuable theoretical insights and technical support for fatigue damage assessment and life prediction of high-speed wheel-rail systems.