Analysis On Elastoplastic And Ratcheting Effect Of Rolling Contact Between Wheel And Rail

In recent years, with the rapid development of EMU in our country, operating mileageincreased, operating speed gradually increased, and this will produce a series of new problemsand challenges. The problem of the wheel-rail contact is one of the key issues. It relates EMUoperator safety, comfort and economy. An effective solution for this problem has importantsignificance for security operations and reducing transportation costs as well as thedevelopment of high-speed trains.With the development and mature of finite element techniques, using the finite elementmethod to solve the wheel-rail contact problem becomes simple and quick, and it be able toget a more accurate analysis results. Wheel under the axle load and traction torque, theelastic-plastic analysis is the main of the wheel-rail contact analysis. And when the wheel onthe rolling process，the main problem is progressive plastic deformation of wheel-rail （ratcheteffect of the wheel-rail rolling contact） produced by the cyclic loading between wheel andrail.In this paper, taking the EMU of CRH₂for example and using nonlinear finite elementsoftware ABAQUS to analyze the elastic-plastic and the ratchet effect of the wheel-railcontact, the main tasks are as follows:（1） Established the finite element model of the wheel-rail contact over a straight-lineconditions. Different axle load, different traverse, different yaw angle, different axleinterference,different traction torque, and different friction coefficients on the wheel-railcontact characteristics was analyzed. And the law of the stress and strain of the wheel-railcontact with the above factors was explored.（2）The wheel-rail contact finite element model over turnout frog conditions wasestablished. Internal stress, contact stress, contact state of wheel-rail under the condition ofwheel abutting guard rail was analyzed. The results show that the heart rail of frog districtsuffered a large stress and severe plastic deformation. It is easy to wear and damage.（3）The finite element model of the wheel-rail rolling contact was established. Andanalysis of the wheel-rail rolling contact characteristics under cyclic loading was completed which using nonlinear isotropic/kinematic hardening model of the ABAQUS which considerthe ratchet effect. According to the theoretical results and current status of research data,preliminary analysis of track damage of wheel and rail produced by ratchet effect wasaccomplished. The results show that with the increase in the number of wheels rolled, theMises stress of rail gradually reduced and residual Mises stress increased gradually, and theystabilized after rolling10times. Ratcheting of plastic deformation first increased and thendecreased, at the end it eventually tended to zero. And the rail materials reached ratchetstability state.Through the above research, it not only provides a theoretical basis for the CRH₂EMUwheel-rail contact but also lay a theoretical foundation for further study of the wheel and raildamage under the ratchet effect.