Research On Interference Fit Behavior Of CRH Wheel Axle And Bearing

With the increasing speed of CRH,wheel axles are subjected to more complex alternating loads and road spectrum vibration impacts,which aggravate the fatigue damage.Bearing is the key component of connecting wheel axle and bogie.It is connected with wheel axle by interference fit and its main failure form is local fatigue damage.It is basically regarded as an ideal 2D axisymmetric model,the influence of surface roundness defects caused by machining accuracy is not considered.Therefore,it is hard to explain the mechanism of local early fatigue damage.This paper is to establish a random roundness model to analysis the non-uniform distribution of pre-stress through pressing simulation,which provides a theoretical basis for the subsequent local stress fatigue damage mechanism of wheel axle and bearing.The specific studies are as follows:(1)Research on 3D modeling with random characteristics.By analyzing the factors affecting the contact stress non-uniformity of wheel-axle bearing,it is determined that the random outline error is the main factor affecting the contact stress non-uniformity distribution.The 2D ideal axisymmetric model is transformed into 3D random contact model.The random interpolation points of roundness profile are obtained by Multiplying Congruence Method,and the Piecewise Cubic Hermite Interpolation Method is used to describe the roundness model of wheel axle,and the Finite Element Model of 3D solid pressing simulation of wheel axle and bearing is established.(2)Study the effect of interference magnitude and random roundness defects on contact stress.It is found that random roundness error is the main reason for non-uniform distribution of contact stress.Under the combined action of cyclic load and alternating external load caused by non-uniform stress during operation,the local fatigue failure of bearings will be aggravated,and the stress distribution in the elastic range is proportional to the interference magnitude.The mechanism of non-uniform distribution of contact stress in interference fit is revealed.(3)Monitoring and analysis of the bearing life cycle is carried out based on Acoustic Emission.The test is carried out on a rolling vibration test rig,the non-uniform stress distribution on the contact surface will aggravate the initiation and expansion of the damage.The description of operation state under the condition of this group of models provides an analysis basis for bearing fault diagnosis.