Research On Service Damage Tolerance And Residual Life Evaluation Method Of High-speed Train Axle

During service,the high-speed train axle often suffers surface damage caused by foreign body impact,which will promote crack initiation and growth.Fatigue crack growth causes fatigue fracture of axles.Statistics show that fatigue fracture axles account for two-thirds of the total number of failed axles.Flaw detection is the main method to evaluate the service safety of axles,but at present,the setting of evaluation indexes for axle detection is not reasonable and effective specifications have not yet been formed.This paper takes the high-speed train power axle as the research object and carries out the research on the service damage tolerance and remaining life evaluation method of axle by combining simulation with test.The main contents of this paper are as follows:(1)Bench Test Study on fatigue crack growth on axle outer surface.The fatigue growth test of a cracked axle has been completed on a full-size fatigue test rig for a wheel axle.Based on the fatigue damage tolerance design method,the bilinear Paris formula which conforms to the laws of crack initiation and propagation on the outer surface of the axle has been obtained.(2)The Simulation Research on the influence law of axle prefabrication defects on stress is carried out.The simulation model is established by ABAQUS software and its validity is verified by comparison.For different working conditions,the stress distribution of axle is analyzed.The results show that with the increase of prefabricated defect size,the maximum stress on axle surface has experienced three stages: rapid increase,stress stability and re-increase.(3)Based on the co-simulation of ABAQUS and FRANC3 D software,the influence laws of depth,shape ratio and form of initial crack on the remaining life of axle are studied.The simulation results show that the residual life of axle decreases with the depth of chordal initial crack increasing under different operating conditions.When the depth of the initial crack is constant,the remaining life of the axle increases with the increase of the shape ratio of the initial crack.The shape ratio and form of the initial crack have a much smaller effect on the remaining life of the axle than the depth.(4)The stress field analysis of axle and the simulation law of crack growth in different parts of its outer surface were carried out by using the loads corresponding to the standard fatigue limit.According to the requirements of ultra-high-cycle fatigue cycle operation of the axle,the damage tolerance size and the residual life evaluation method of the crack on the outer surface of the axle are determined.This paper can provide scientific basis for revision of flaw detection specification,prediction of remaining life and service safety evaluation of hollow axle of high-speed train,and has certain theoretical value and engineering application value.