钢轨表面剥离掉块路径预测研究

轮轨滚动接触下,钢轨表面会产生典型的鱼钩形剥离掉块,其形成机理目前暂未明确.为了探究轮轨滚动接触下钢轨表面裂纹扩展机理,基于最大周向拉应力准则,建立轮轨滚动接触疲劳计算模型,提出裂尖扩展路径预测方法,并对不同初始角度裂纹的扩展路径进行预测.结果表明,钢轨表面微裂纹为Ⅰ-Ⅱ复合型裂纹,随着裂纹长度增加,KⅠ先增加后减小,...

Study on path prediction of spalling defect on rail surface

Under the wheel/rail rolling contact force,the rail surface will produce typical fishhook shaped spalling defect,and its formation mechanism is not clear at present.In order to explore the propagation mechanism of rail surface cracks under the wheel/rail rolling contact force,the fatigue calculation model of wheel/rail rolling contact was established and the prediction method of crack propagation path was proposed based on the maximum circumferential stress criterion.The results show that,the surface microcracks of the rail belong to the I-II mixed cracks.With the increase of crack length,the stress intensity factor K_I increases firstly and then decreases.However,the K_II shows a trend of continuous increase.When the crack grows to a certain depth,the driving force of crack propagation changes from K_I to K_II.At this point,the crack tip will turn about 70° under the drive of K_II,and tends to propagate upward and leads to fishhook shaped spalling defect.The angle of initial crack on rail surface has an obvious influence on the path of the spalling defect,but has little influence on the depth of the spalling defect.The research results of this paper provide a theoretical basis for the formulation of maintenance regulations for rail surface grinding.