Fatigue Analysis Of EMU Wheel Rim With Inclusions

As one of most significant components of the railway system,EMU wheels play the role in bearing loads and guiding,and it is the vital unit guaranteeing the safety of railway train.With the improvement of vehicle and load,more and more train safety issues appear,so the requirement of its security and the safety has been posed.Both the analysis failure mechanism of railway wheel and the evaluation safety under the conditions of service are of great importance for the train security.Focusing on the typical failure modes-the deep shelling of wheel rim,the typical failure mechanism and fatigue life of EMU wheel are studied.The contents are as following:Firstly,According to the standards of UIC510-5 and BSEN13979,the loads of EMU wheel are calculated respectively in straight track and curved track as well as switches and crossings.The local mechanical behavior around the inclusions of wheel rim is investigated in different load cases using elastic-plastic finite element model.The results show that the maximum stress around the inclusion is relatively obvious in the curved track comparing with the other two cases.It means that the wheel rim with inclusion trend to generate fatigue crack in this case.Secondly,the critical inclusion size in wheel rim is calculated according to the following three load cases,straight track and curved track as well as switches and crossings.The relationship of the critical inclusion size and fatigue limit is deduced by Murakami theory;The maximum principal stress around inclusions varying size is analyzed by FEM;And the relationship of the maximum principal stress and the critical size is fitted.According to the above-mentioned relationship,the critical inclusion size can be calculated.The results show that the critical inclusion size in wheel rim beneath tread 10 mm is smallest,and in the same condition,the closer to the tread of wheel the inclusion is,the smaller the critical size.Then,The influence of inclusion shape and size on local stress and crack nucleation in CRH5 wheel rim is analyzed by finite element method(FEM).Results show that the sharper the inclusion,the greater the stress level of wheel rim.And the local stress increase with the decrease of inclusion thickness and the increase of inclusion radius.And it leads to increase of local stressconcentration factor around the inclusion,which indicates a transferred fatigue crack initiation.The broken inclusion caused by stress concentration and slip band or cavity all easily make matrix fatigue crack generate.Last but not the least,the fatigue life of wheel rim with inclusion is estimated in curved track case,and compared with the fatigue life of wheel rim without inclusion.The result shows that the fatigue life of the rim is significantly shorter when the inclusions are present.These studies in this paper are important to analyze reliability of EMU wheel,which will provide support of theory and technology for reliability analysis model and also provide support for security service of domestic EMU wheel.