中文摘要：

在分析典型滚动接触疲劳裂纹扩展特征,介绍垂向磁化检测原理及巡检方法的基础上,提出了一种采用垂向磁化场对钢轨疲劳斜裂纹进行电磁检测的方法。通过建立有限元模型,仿真分析了表面斜裂纹与钢轨顶面夹角、沿轨面下转向扩展角度、扩展深度及延伸长度、近表面裂纹埋藏深度与垂向磁化检测信号的关系。结果表明,该方法能有效检测材料表面和近表面斜裂纹及其沿轨面下的扩展特征,有助于高速铁路钢轨疲劳伤损的检测和故障早期预警。

英文摘要：

This paper proposed an electromagnetic NDT method for inspection and characterization of railhead fatigue oblique crack using vertical magnetization.The characteristics of natural crack initiation and propagation induced by rolling contact fatigue（RCF）were analyzed and simplified for theoretical investigation of vertical magnetization test.The relationship between detection signals and crack dimensions,such as inclined angle with running surface,growth path with different turning angles,propagation depth and length of surface crack and buried depth of sub-surface crack,were provided by carrying out 2-D static FEM simulation.The results demonstrated that this approach could effectively recognize surface and sub-surface oblique crack and their propagation characteristics.This approach is suitable for rail RCF damage inspection and fault early warning of high speed railway.