Comparative Study Of Non-Hertzian Wheel-Rail Rolling Contact Models

The wheel-rail contact relationship is a key issue for vehicle dynamics calculations and research on wheel-rail wear.The classic hertz theory cannot accurately reflect the real contact behavior between wheel and rail,and a series of algorithms have emerged.This paper focuses on six simplified non-hertz contact algorithms to study the influence of different contact models on the calculation of wheel-rail contact behavior,dynamic simulation and prediction of wheel wear.(1)First,the development process of wheel-rail rolling contact calculation methods were summarized and the existing contact calculation methods were introduced,the significance of studying the interaction between wheel and rail was clear,and the contact method for calculation and analysis were determined.(2)Next,this paper systematically studies six simplified contact models for normal contact calculations,including the KP model based on the virtual surface deformation method,the STRIPES model,and the ANALYN model using the approximate surface deformation method.The EKP,MKP,and MSHM models that were newly developed in the year considering the shaking of the head.Kalker’s complete theoretical program CONTACT was taken as a standard comparison,the accuracy and stability of its normal contact are analyzed.The results show that,except for extreme non-hertz contact conditions,all six simplified contact models can obtain satisfactory contact spot shapes and normal contact stress distributions.Among them,the KP model and the MKP model take into account accuracy and stability.And the yaw angle has little effect on the normal calculation.(3)Two tangential contact algorithms FASTSIM and Fa Strip are implemented,and different tangential algorithms are adapted to the above six simplified contact algorithms through the equivalent ellipse method or local ellipse method for tangential contact calculation.After completing the normal and tangential calculations,this paper selects the USFD model to calculate the accuracy of different simplified contact algorithms to predict wheel wear.The results show that the ANALYN,MKP,and EKP models using Fa Strip as the tangential algorithm can obtain more accurate tangential stress distributions,while the FASTSIM algorithm will incorrectly estimate the adhesion distribution due to the use of unreal parabolic boundaries.EKP model,MKP model,and MSHM model can improve the prediction accuracy of wheel wear,while the yaw angle will increase the energy index in the contact spot,which may cause greater wear.When the contact spot with a large yaw angle is in a fully sliding state,it is not appropriate to use the MSHM model to predict wear.(4)In this paper,two methods are used to analyze the influence and applicability of simplified algorithm involved in dynamic calculation.The results show that in dynamic analysis,the shape number that measures the non-Hertz degree of the contact patch is the main factor that affects the contact calculation accuracy.Based on the calculation results in this paper,it is recommended that when the shape number is less than 0.4,the Hertz model can meet the calculation accuracy requirements.When calculating large non-Hertzian conditions with shape number greater than 0.4,the MKP model can always maintain good accuracy and efficiency.