滚动接触疲劳短裂纹扩展机制及预防研究

Propagation Mechanism and Prevention of Rolling Contact Fatigue Short Crack

采用有限元分析软件ANSYS,在无摩擦、纯滚动、全滑动三种运行状态下,研究钢轨表面短裂纹的疲劳断裂机制,并分析轮轨间摩擦因数对接触疲劳裂纹扩展速率的影响。结果表明,轮轨接触的疲劳裂纹为张开型和滑开型同时存在的复合型裂纹,裂纹发生张开型破坏的最危险位置在接触斑边缘的位置;随着裂纹角度的增加,应力强度因子KI增加而KII减小,其中60°裂纹的扩展速率最快;摩擦力的存在明显加剧了裂纹扩展速率,且随着摩擦因数的增加而增大。对钢轨表面预防性打磨周期进行预测时,以60°裂纹为基准的预测结果偏安全。

The finite element method software ANSYS was used to analyze the mechanism of fatigue of rail surface short crack under the different operating statuses including friction-free,pure rolling and complete sliding,and the effect of friction coefficient on the propagation rate of contact fatigue crack was analyzed. The results show that,the mixed mode of wheel/rail contact crack includes sliding mode and opening mode,and the most dangerous location of opening mode crack is at the edge of the contact area. With the increase of the crack angle,the stress intensity factor KIis increased,but the KIIis decreased. The rate of crack propagation with 60° angle is the fastest. The crack propagation rate is increased significantly with the increase of the friction coefficient. It is safety to buff the rail surface by using the buffing period calculated based on the 60° crack.