高速铁路钢轨波磨高发区段弹条断裂机理研究

Fracture mechanism of elastic bar in high-incidence section of rail corrugation of high-speed railway

我国高速铁路钢轨在长期应用中出现了大量波浪形磨耗(简称钢轨波磨),且在钢轨波磨高发区段伴随着大量扣件弹条的断裂问题,具有重大安全隐患。为探究我国高速铁路扣件弹条在钢轨波磨高发区段的断裂机理,首先现场调研掌握了广深高铁波磨区段的弹条断裂情况,并构建了波磨高发区段的轮对-钢轨-扣件系统有限元模型;然后从共振特性角度,对比分析了波磨诱导的轮轨系统振动与扣件弹条的固有振动特性;进而从疲劳特性角度,基于线性累积损伤理论分析了扣件弹条的疲劳寿命;最后,从波磨特性与弹条扣压的角度,提出了相应的高速铁路钢轨波磨区段扣件弹条断裂的控制方法。研究结果表明:在钢轨波磨高发区段轮轨激励频率与安装状态下弹条的固有频率相近,由此产生的共振现象可能是导致弹条断裂的主要成因;轮轨激励造成的剧烈振动使弹条疲劳寿命急剧降低,计算寿命为39.5万次,明显低于设计寿命500万次的要求;通过控制钢轨波磨深度,保证弹条正常扣压的方法,均可以有效保证扣件弹条使用寿命。

In long-term application of high-speed railway rails in China,a large amount of wavy wear,i.e.,rail corrugation appears,it is accompanied by fracture of a large number of fasteners and elastic bars in high incidence section of rail corrugation to have serious safety risks.Here,to explore the fracture mechanism of elastic bar of high-speed railway fastenings in high incidence section of rail corrugation in China,fracture situation of elastic bars in corrugation section of Guangzhou-Shenzhen high-speed railway was firstly investigated and mastered on site,finite element model of a wheelset-rail-fastening system in corrugation high incidence section was constructed.Then,from the perspective of resonance characteristics,a contrastive analysis was performed for vibration of wheel-rail system induced by corrugation and natural vibration characteristics of fastener elastic bar.Furthermore,from the perspective of fatigue characteristics,the fatigue life of fastener elastic bar was analyzed based on the linear cumulative damage theory.Finally,from the perspective of corrugation characteristics and elastic barclamping-compressing,a corresponding control method for fracture of fastener elastic bar in high-speed railway rail corrugation section was proposed.The study results showed that the excitation frequency of wheel-rail in high-incidence section of rail corrugation is close to the natural frequency of elastic bar under installation condition,the resulting resonance phenomenon may be the main cause of elastic bar fracture;severe vibration caused by wheel-rail excitation sharply reduces fatigue life of elastic bar,its calculated fatigue life is 395000 cycles,and obviously lower than the design life requirement of 5 million cycles;by controlling depth of rail corrugation and ensuring normal clamping of elastic bar,the service life of fastener elastic bar can effectively be guaranteed.