摘要
采用X射线断层扫描技术测量重载铁路钢轨轨顶面弯钩形滚动接触疲劳裂纹,根据非均匀有理B样条方法实现了曲面裂纹的空间三维重构,建立弯钩形裂纹的双曲面模型,提出基于扩展有限元的弯钩形曲面裂纹扩展预测方法,研究不同深度裂纹在空间上的扩展特征。结果表明,在轮轨接触荷载作用下,弯钩形裂纹的扩展是张开、滑开和撕开效应结合的复合开裂;对于深度较浅的裂纹,即尚未发生路径转变的1/3、1/2深度裂纹,其扩展明显;当裂纹扩展到一定深度、发生路径转变后,裂纹的扩展逐渐降低,形成明显的弯钩;裂纹尖端不同位置应力强度因子不同,空间上以一定角度呈“凸”字形不均匀发展;预测得到通过总重在100~150 MGT裂纹扩展长度最大为0.389 mm,扩展最快位置在裂纹尖端中部附近,转向后弯钩形裂纹扩展角度范围为15°~35°,与显微观测的实际裂纹接近。
The hook-type cracks(HTCs)on the surface of the rail from a heavy-haul railway in China were inspected by X-ray Computed Tomography scan technology(CT scanning).According to the non-uniform rational B-spline(NURBS)method,the three-dimensional(3D)shape of the real HTCs were reconstructed and the hyperboloid model of the hook-type crack was established.The HTCs propagation prediction method was presented and used to study the propagation characteristics of cracks with different depths in 3D space.The results show that the HTC propagation was a composite mode with opening,shearing and tearing effects under the wheel-rail contact load.For the HTCs with 1/3 and 1/2 depth to the whole one which have not yet undergone route change,their propagation is obvious.When the HTCs expand to a certain depth to change their route,the crack propagation decreases gradually and forms an obvious hook.The stress intensity factor(SIF)at each position of the crack tip is different causing inhomogeneous propagation in the shape of convex along the crack tip with a certain angle.The predicted maximum crack propagation length is 0.389 mm at the top of the crack tip.The fastest propagation position is near the middle of the crack tip.The HTCs propagation angle after route change is 15°~35°,close to the actual HTCs by microscopic observation.
作者
李骏鹏
周宇
梁旭
王钲
卢哲超
程中宁
LI Junpeng;ZHOU Yu;LIANG Xu;WANG Zheng;LU Zhechao;CHENG Zhongning(The Key Laboratory of Road and Traffic Engineering of the Ministry of Education,Tongji University,Shanghai 201804,China;Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety,Tongji University,Shanghai 201804,China;Metals&Chemistry Research Institute,China Academy of Railway Sciences Corporation Limited,Beijing 100081,China)
出处
《铁道学报》
EI
CAS
CSCD
北大核心
2022年第7期125-134,共10页
Journal of the China Railway Society
基金
国家自然科学基金(51878661)
上海市2020年度“科技创新行动计划”社会发展科技攻关项目(20dz1203103)。
关键词
重载铁路
钢轨
滚动接触疲劳
弯钩形裂纹
三维重构
裂纹扩展
heavy-haul railway
rail
rolling contact fatigue
hook-type crack
3D reconstruction
crack propagation
