高速铁路无砟轨道扣件弹条断裂原因分析

Analysis of elastic bar fracture causes of fasteners in ballastless track of high-speed railway

为研究高速铁路无砟轨道扣件系统中的弹条部件断裂原因,以WJ-7型扣件为研究对象,建立扣件系统有限元实体模型,分析扣件安装、车轮多边形磨耗及曲线线型等3种条件下的扣件弹条力学特征。研究结果表明:预紧力到24 kN时扣件安装到位,即使无其他荷载作用,弹条本身就已存在相当大的应力值,过拧将继续增大应力值;车轮多边形磨耗阶数的提高会增大弹条应力值,3阶磨耗时应力增量36MPa,较无磨耗增大5倍,疲劳寿命较无磨耗状态降低95%;曲线半径减小和车速提高将增大弹条应力,降低其疲劳寿命,其中半径影响更显著,半径4 000 m时弹条寿命2万次,较8 000 m减少98%以上。本文可为扣件的养护维修提供参考。

In order to analyze the reasons for the fracture of fastener elastic bar of ballastless track in high-speed railway, the WJ-7 fastener was taken as the research object and a finite element solid model of fastening system was established. Based on the model, the mechanical characteristics of fastener elastic bar in the process of installation, the wheel polygonal wear and the condition of curved line were analyzed. The results show that the fasteners are installed in place when preload is 24 kN, even if there is no other load, the bar itself has a considerable stress value and it increases with over-twisting. Increasing number of wheel polygonal wear order can lead to the raising stress of bar. The third-order wear stress increment is 36 MPa, which is 5 times more than non-wear, and the fatigue life is 95% lower than the wear-free state. When curve radius decreased and speed lifted, it leads to the raise of elastic bar stress and decrease of fatigue life, especially with the influence of radius. The fatigue life of bar is 20 000 times when radius 4 000 m, which is reduced by over 98% compared with radius 8 000 m. This paper can provide reference for maintenance and repair of fasteners.