高速铁路道岔曲尖轨疲劳裂纹萌生预测

Prediction of Fatigue Crack Initiation in Curved Switch Rail of High-speed Railway Turnout

摘要:

针对高速铁路道岔曲尖轨疲劳裂纹与磨耗共存发展的情况，提出考虑磨耗的高速铁路道岔曲尖轨裂纹萌生预测方法。以列车侧向?逆向过岔时的轮载转移、轮轨接触状态为例，结合曲尖轨和基本轨的廓形关系，再现曲尖轨磨耗和疲劳累积过程，并分析曲尖轨磨耗和疲劳损伤发展特征、轮载转移和轮轨接触变化，从而预测曲尖轨裂纹萌生寿命和位置。结果表明，考虑列车逆、侧向通过的情况，在曲尖轨裂纹萌生过程中，各磨耗阶段内达到磨耗阈值所需的通过总重呈波动变化，即磨耗发展不规则，且基本轨和曲尖轨的磨耗发展率呈相反趋势；曲尖轨顶宽35 mm断面处疲劳裂纹萌生寿命约11.7 MGT（百万吨），裂纹萌生位置在轨顶区域内距轨顶中心10~15 mm、钢轨表面1~3 mm处。

Abstract:

In view of the co-exitance of rolling contact fatigue （RCF） crack initiation and wear growth in the curved switch rail of high-speed railway turnout， a prediction method of RCF crack initiation considering the wear in the curved switch rail was proposed. Taking the wheel loading position transfer and wheel-rail contact status when passing turnout along reverse and side direction as an example， and considering the profiles relationship between curved switch and stock rails， the wear and fatigue accumulation process of the curved switch rail was recreated. The development characteristics of wear and fatigue damage in the curved switch rail， changes in the wheel loading position transfer， and wheel-rail contact conditions were analyzed for predicting the initiation life and location of cracks in the curved switch rail. The results indicate that the traffic gross tonnage at each wear growth phase shows a fluctuation trend， which means that the wear grows with an irregularity process， during the process of crack initiation considering train passing with reverse and side direction. Moreover， a contrasting trend was observed in the wear growth rate between stock and curved switch rails. The RCF crack initiation life for a section with a top width of 35 mm of the curved switch rail is estimated to be approximately 11.7 MGT （million gross tonnage）. The crack initiation position is located at an area on the top of the rail about 10-15 mm away from its center and 1-3 mm below its surface.