构架裂纹扩展延迟效应

列车运行速度的提高和载重量的增加使其主要承载部件转向架构架的运行环境变得恶劣。为减小轮轨间的作用力 ,要对构架进行轻量化设计 ,由此引起了构架疲劳强度问题。对某高速列车构架的疲劳试验结果表明 ,在给定的常规载荷作用下构架裂纹扩展速度出现延迟效应 ,最终减小到零。应用弹塑性裂纹扩展与闭合概念和残余应力松弛概念分析了构架裂纹扩展延迟效应 ,结果表明引起构架裂纹扩展速度减慢的主要因素是循环加载中残余应力的松弛 ,而裂纹的闭合对裂纹的延迟也有重要影响 ;计算了给定工艺构架状态和循环载荷下 ,不扩展裂纹初始长度的最小值

Defer effects of crack propagation of bogie

With the enhancement of the speed and the load capacity of rail vehicles,the running conditions of bogie frame and the main supporting parts of rail vehicle become worse.In order to reduce the interaction force between rail and wheel,the weight of the frame has to be optimized.Thus the fatigue strength of the bogie is of concern.The fatigue experimental results of a high speed train show that the crack propagation of the frame slow down under the cyclic loads.The concept of relaxation of residual stress under cyclic loads and open and close of crack are utilized to analyze the effects of crack propagation.The analysis shows that the main reason of the crack propagation slow down of the frame is the relaxation of the residual stress under the cyclic loads.Crack close also affects the crack growth greatly.The maximum allowable length of non propagation crack is calculated under the given configuration and cyclic loads.2 tabs,6 figs,7 refs.