| As one of most significant components for the train bogie system, EMU wheel is one of themost demanding parts for its severe service conditions, and it is also the vital unit guaranteeingthe safety of railway train. The higher speed the vehicle is, the higher requirement for its securityand reliability has to be posed. Both the analysis failure mechanism of railway wheel and theevaluation 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), fatigue life andreliability-based sensitivity of EMU wheel are studied. The contents are as following:Firstly, considering elasto-plastic contact of wheel/rail, the stress/strain state of the wheel rimis analyzed. According to elasto-plastic finite element analyses, it’s obtained that stressconcentration is presented on the wheel/rail contact surfaces and the wheel rim. The stress valueis higher than the yield stress limit of rim material, and a certain plastic deformation is developedon the stress concentration region. Owing to a maximum deformation in the wheel rim, the wheeldeep shelling is probably generated in this region.Secondly, the fatigue life of wheel rim is estimated according to the following load cases,straight track and curved track as well as switches and crossings. According to relevant standardsand the actual load conditions, the corresponding load spectrum is obtained by theoreticalcalculating. Based on S-N curve and Miner’s rule and the corresponding stress spectrum of FEMmethod, the fatigue life of wheel rim is calculated in these load cases. The results show that it hasa worse effect on the fatigue life in the switches and crossings, and it has a minute effect on thefatigue life in the straight track and curved track.Then, it is determined that the type, position, size and aggregation of inclusions effect on rimlocal stress and fatigue crack initiation, through analyzing the effect of different inclusions ofAl2O3and MnS with different sizes and positions. The broken inclusion caused by stressconcentration and slip band or cavity all easily make matrix fatigue crack generate. The initiationand propagation of fatigue crack will be sustained and the wheel rim will be fatigue failure.Last but not the least, it is essential to make fatigue reliability analysis about impacts on wheelrim with the factors varying the distribution of the inclusions, position from the materialproperties and the size of inclusions the rim. Based on Monte-Carlo analysis method with largenumbers of samples, reliability sensitivity of wheel rim containing inclusions is analyzed. It’s obtained that the most sensitive factor for reliability is the size of inclusions and the next ismaterial properties, while the size of inclusions has little effect on the reliability.These studies in this paper are important to analyze reliability of EMU wheel, which willprovide support of theory and technology for reliability analysis model and also provide supportfor security service of domestic EMU wheel. |
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