摘要
采用X射线断层扫描技术测量钢轨轨距角–轨肩的滚动接触疲劳裂纹,通过裂纹平面化、尖端拟合和空间定位,重构真实裂纹的三维形态和空间位置;考虑裂纹尖端塑性区和磨耗的影响,提出基于三维重构的裂纹扩展预测方法。预测结果表明,X射线断层扫描技术可以得到真实裂纹的高精度形状和特征,实现钢轨轨距角–轨肩处近似平面状裂纹的三维建模。根据重载铁路典型的车辆和曲线轨道条件,预测裂纹在一定通过总重累积下的扩展情况,接触斑作用在裂纹上时引起的应力最大值集中在轨面及轨面以下垂直深度2~4 mm处,裂纹尖端及裂纹开口附近未出现应力集中;一、三位外轮和二、四位外轮引起的裂纹尖端节点的Von-Mises应力分别相近;当前轮与外轨发生两点接触时,前轮接触斑下方的裂纹尖端节点应力小于后轮引起的应力;预测的裂纹长度、深度与显微观测的实际裂纹接近,预测的裂纹沿钢轨纵向扩展的角度范围包含了显微观测的实际扩展角度。
The head checks(HCs) at the gauge corner and shoulder of the rail from a heavy-haul railway in China are inspected by X-ray Computed Tomography scan technology(CT scanning). The three dimensional(3D) shape and space position of the real HCs are reconstructed by HCs planarization, HCs tip shape fitting and HCs plane space localization. The rail HCs propagation prediction method is presented in which the influence of the plastic zone at the HCs tip and are were considered. The results show that the CT scanning technology can get high-precision shape and characteristics of the real complete HCs, which realizes the 3D modeling of the nearly-flat HCs at the gauge corner and shoulder of the rail. The HCs propagation is predicted with the traffic accumulation according to the vehicle and track condition of the heavy-haul railway in China. It is shown that the maximum stress of the HCs by wheel/rail contact patch is at the rail surface and sub-surface with vertical distance of about 2-4 mm. There is no stress concentration at both the tip and the mouth of the HCs. The Von-Mises stress at the HCs tip by both leading outer wheels and both trailing outer wheels of the front and rear bogies in the same vehicle are close to each other respectively. The stress at HCs tip points below contact patch caused is by the front wheel smaller than that by the rear wheel when two-point contact happens between the front outer wheel and the high rail. The length and depth of HCs by prediction are close to those by microscopic observation. The propagation angle of the HCs along rail longitudinal direction by prediction includes the real propagation angles range of the HCs by microscopic observation.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2018年第4期158-166,共9页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(51678445)
关键词
钢轨
滚动接触疲劳裂纹
裂纹扩展
X射线断层扫描
重构
rail
rolling contact fatigue crack
crack propagation
X-ray computed tomography scan
reconstruction
