轮轨接触位置对钢轨斜裂纹扩展行为影响的仿真

Simulation Study on the Growth Behavior of Rail Oblique Crack under Various Wheel Rail Contact Positions

采用ANSYS软件，仿真研究不同线路条件下轮轨接触位置变化对钢轨踏面斜裂纹扩展行为的影响。分析表明：轮轨接触位置沿纵向仅在距离钢轨踏面斜裂纹左右各1／4跨距范围内对斜裂纹扩展有突出影响，其余位置影响很小，可以忽略。在直线线路，当轮轨接触位置位于轨顶面中央时，钢轨踏面斜裂纹以Ⅰ-Ⅲ型的复合型方式扩展为主，扩展缓慢；偏离轨顶面中央5mm，钢轨踏面斜裂纹则以Ⅰ-Ⅱ型的复合型方式扩展为主，在踏面以下4mm内可能发生水平转向，5．8～12mm内容易发生横向转向。在800m曲线线路外股，当轮轨接触位置偏离轨顶面中央16．5mm时，钢轨踏面斜裂纹以Ⅰ-Ⅱ-Ⅲ型的复合型方式扩展为主，而且比直线线路扩展迅速；在踏面以下2．1～4．8mm内，斜裂纹可能发生水平转向，而一旦扩展至更深位置时很可能会保持初始角度扩展下去。

Computational simulations with ANSYS software have been performed on the growth behavior of rail tread oblique cracks under various wheel rail contact positions which are caused by different railway line conditions. Analysis results show that, only in the range of a quarter of sleeper spacing from the oblique crack along longitudinal direction of rail, the wheel rail contact position affects crack growth outstandingly, while the rest can be ignored. On straight line, under the condition of wheel rail contact position on the centre of rail head, rail tread oblique cracks mainly propagate as I -III type and grow slowly. Whereas the wheel rail contact position deviates from the centre of rail head 5 mm, rail tread oblique cracks mainly propagate as I - II type. The crack growth may turn into horizontal direction less than 4 mm deep beneath the rail tread, and may turn into transversal direction at the depths of 5.8-12 mm. On radius 800 m curve of the outside rail, under the condition of wheel rail contact position deviates from the centre of rail head 16.5 mm, rail tread oblique cracks propagate as I -II-III type and grow faster than on straight line. The crack growth may turn into horizontal direction at the depths of 2.1-4.8 mm beneath the rail tread. When cracks grow in a deeper position, it is very likely that they may propagate as the same initial angle.