影响钢轨疲劳裂纹萌生寿命的主要因素分析

Analysis of Major Influencing Factors of Rolling Contact Fatigue Crack Initiation Life of Rails

建立了钢轨3维弹塑性有限元计算模型,分析了接触斑内应力-应变场特点.分析结果表明,在接触斑内钢轨处于三向压缩应力状态,有较大的静水压力;认为静水压力影响滚动接触疲劳裂纹萌生寿命.以临界平面法为基础,提出了考虑静水压力影响的滚动接触疲劳裂纹萌生寿命预测模型,分析了轮载和摩擦系数对疲劳裂纹萌生的影响.结合具体算例分析表明:随着静水压力增大,静水压力对滚动接触疲劳裂纹影响在增大;随着轮载和摩擦系数增加,滚动接触疲劳裂纹萌生寿命迅速减少.

In order to analyze the stress-strain field characteristics of rails, a three-dimensional elastic-plastic rail model is established by finite element method. The results show that the stress-strain field of rail at the contact patch is in a three-compression-stress state, with much greater hydrostatic stress. Rail rolling contact fatigue （RCF） crack initiation life is very sensitive to hydrostatic stress. Based on the critical plane approach, a new prediction model is established by taking into the consideration the effects of hydrostatic stress on the rolling contact fatigue crack initiation life. An analysis is made of the effects of wheel load and friction coefficient on the basis of the model. U71Mn rail steel is investigated in detail to validate the proposed approach. The results show that, as the hydrostatic stress increases, the effects of hydrostatic stress on the rolling contact fatigue crack initiation life become greater and as the wheel load and the friction coefficient increase,fatigue life to crack initiation decreases significantly.