时速200km·h^(-1)铁路道岔60AT尖轨锻压过渡段疲劳试验早期断裂原因分析

Reasons Analysis on Early Fatigue Fracture of Forging Transition Section of 200km·h^(-1) Railway Turnout 60AT Switch Rail

针对时速200km·h-1铁路道岔60AT尖轨锻压过渡段依照TB/T 1354-1979进行实物疲劳试验发生早期断裂的情况,对尖轨疲劳断口进行了宏观分析和理化性能试验分析,建立了钢轨疲劳试验件的有限元实体模型并进行了有限元仿真受力分析。结果表明:尖轨锻压过渡段短肢和长肢轨底最大Mises等效应力比为2.26,且有限元求解得到的最大应力值为解析法求解得到的最大应力值的1.2倍,最大应力位置出现在尖轨变截面段起始处的短肢侧,与疲劳试验过程中钢轨断裂源位置相吻合;因而载荷过大是造成尖轨锻压过渡段疲劳试验早期断裂的主要原因。

For the situation that the forging transition section of 60AT switch rail for 200 km ~ h ＇ railway turnout fractured early when fatigue test refering to TB/T 1354- 1979, macro analysis and physicochemical performance test were done to the fractured rail, and the finite element solid model of the rail fatigue test piece was established and FEM force analysis was done. The results show that the biggest Mises equivalent stress ratio of rail bottom short leg and long leg was 2. 26, and the maximum stress value obtained by finite element solution was 1.2 times of that by ayalytic method. The maximum stress position appeared at the short leg of variable cross-section beginning location. It coincided with the rail fracture source location during the fatigue test. So it could be conduded that the excessive load was the main reason of early fracture of forging transition section of the 60AT switch rail in fatigue test.