Study On Rolling Contact Fatigue Failure Of Wheel Tread

Wheel/rail rolling contact fatigue damage is a difficult technical problem in railway industry.With the improvement of train speed,axle load,wheel/rail rolling contact fatigue damage phenomenon is becoming more and more serious,leading to higher cost of railway transportation,a direct impact on the safety of railway transportation.Although there is a certain degree of understanding of the wheel/rail rolling contact fatigue damage through theoretical and numerical methods,the formation mechanism of different types of fatigue damage is not completely understood and mastered.Therefore,it has important theoretical significance and engineering application background to carry out research on wheel/rail rolling contact fatigue damage.In this paper,the classification of wheel/rail rolling contact fatigue damage and its research history and current situation are discussed in detail.Mainly to the wheel tread rolling contact peeling damage phenomenon as the research object,based on the combination of wheel/rail rolling contact theory and finite element simulation method,study on the formation mechanism of wheel tread peeling damage under rolling contact condition.The main research contents are as follows:1.A three-dimensional elastic-plastic finite element model of wheel rolling contact is established.Model in the contact patch shapes,adhesion and sliding partition,contact method to the stress and shear stress distribution by Kalker's non Hertzian rolling contact theory to determine.A cyclic plastic constitutive model is used to describe the plastic accumulation of the material,The residual stress,strain and deformation of the wheels under different rolling contact conditions were studied,and the changing law of the stress,strain and deformation of the wheel was obtained vunder the condition of cyclic rolling contact.2.Based on the wheel rolling contact of 3D elastic-plastic finite element model,the simulation results and multiaxial low axial fatigue model combined with to predict wheel material in rolling contact fatigue crack initiation position,angle and the initiation of the cycle number.Finally,the rolling contact fatigue life analysis results are compared with the existing rolling contact fatigue test results,which verify the feasibility of the rolling contact fatigue life prediction method.3.A two dimensional finite element model of the wheel with defect hole is established.In the model,the residual deformation and accumulation of the hole of the wheel material under the condition of cyclic rolling contact are considered.The based on strain fatigue damage parameter and based on the critical plane multiaxial low cycle fatigue model to study the method to contact load,defect hole depth and friction coefficient of material defect hole fatigue damage parameter and fatigue crack initiation cycles,fatigue damage parameter under the influence of different parameters along the periphery of a defect hole distribution.4.Surface oblique crack,sub surface crack and surface crack of three different forms of two-dimensional finite element model is established,using the theory of linear elastic fracture mechanics analysis of the variation of the stress intensity factor in crack tip wheel under the action of moving loads.The influences of vertical contact load,surface friction coefficient,crack surface friction coefficient,crack length,crack angle and multi crack spacing on the stress intensity factor of the crack tip were studied.Based on the variation of stress intensity factor at the crack tip,the behavior characteristics of the crack under different action conditions are analyzed.5.Based on the above of different forms of crack tip should study on stress intensity factor,which can be used in the multi axis and non-proportional loading conditions of crack expansion angle criterion of different crack types under various conditions of crack propagation behavior,reveals the wheel tread material debonding failure mechanism.6.The coupling relationship between wheel/rail rolling contact fatigue crack growth and wheel/rail material wear is studied.The wheel/rail surface crack propagation and wear coupling analysis model,analysis the influence of surface friction coefficient,the maximum contact pressure,crack surface friction coefficient and wear coefficient of different parameters,material wear on the effect of rolling contact fatigue crack propagation.