目的 利用有限元软件ANSYS对车轮滚过裂纹过程进行分析,确定轮轨接触疲劳裂纹的扩展方向. 方法 基于最大周向应力判据,用概率统计的方法对车轮滚过裂纹过程中,不同角度初始裂纹可能的扩展角度进行分析. 车轮滚过裂纹过程中,用可能扩展角度的均值作为裂纹的扩展方向计算裂纹扩展路径. 结果 用概率坐标纸拟合出的相关系数均大于98 . 5%,说明裂纹可能的扩展角度符合威布尔分布的可能性超过98 . 5%. 当裂纹长度小于700 μm时,裂纹可能的扩展角度基本符合威布尔分布;当裂纹长度达到800 μm时,裂纹尖端的等效应力强度因子( Kef )出现4个峰值;当裂纹长度达到1200 μm时,第3个峰值载荷处裂纹尖端的Kef超过了材料的断裂韧性,此时裂纹会向行车相反的方向急剧地扩展.结论 对于不同角度初始裂纹,其扩展角度基本符合威布尔分布;整个裂纹路径的趋势与实验测得的裂纹路径有较好的一致性,车轮滚过裂纹过程中,用裂纹可能扩展角度的均值作为裂纹的扩展方向可行.
Objective The process of wheel rolling over crack was analyzed by the finite element software ANSYS, in order to predict the propagation direction of the wheel-rail contact fatigue crack. Methods Based on the maximum circumferential stress cri-terion, the possible propagation direction of initial crack with different angles during the process was analyzed using probabilistic and statistical method. The crack propagation path was calculated using the average propagation angle as the direction of crack propagation during the process of wheel rolling over crack. Results The correlation coefficient fitted by the probability paper was all higher than 98. 5%, indicating that the possibility that the possible crack propagation direction was in line with the Weibull distri-bution was higher than 98. 5%. The possible crack propagation direction was almost in line with the Weibull distribution when the crack length was less than 700 μm. The equivalent stress intensity factor Kef of crack tip began to show four peaks when the crack length reached 800 μm. The crack propagated abruptly in the opposite direction of the train running as the crack length reached 1200 μm when the Kef of crack tip at the 3rd peak load exceeded the fracture toughness of the material. Conclusion For initial crack with different angles, the crack propagation direction was almost in line with Weibull distribution. The whole trend of the crack path was in agreement with the experimental crack path, which proved the feasibility of using the average propagation angle as the crack propagation direction.
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