W300-1型扣件弹条疲劳寿命的预测和评估

Fatigue Life Prediction and Evaluation of the W300-1 Fastening Clip

摘要:

为有效评估和预测W300-1型扣件弹条在实际工作状态下的疲劳寿命，综合考虑弹条材料的弹塑性力学特性及复杂接触关系，建立有限元模型；分析弹条在不同安装扭矩下的受力情况，并用数字图像相关（DIC）测试结果予以验证；基于京沪高铁实测轮轨力时程曲线，施加等效循环疲劳载荷谱，结合弹条材料应变-寿命曲线，预测弹条疲劳寿命；分析安装扭矩、疲劳载荷幅值、以及两者匹配关系（应力比）对弹条疲劳寿命的影响。结果表明：无论处于略微欠拧、正常安装或过拧状态，弹条危险点位置均位于跟端圆弧内表面，已发生塑性变形。弹条疲劳寿命随安装扭矩和疲劳载荷幅值的增加而降低，与危险点应力比呈线性关系。因此，为保证弹条的实际使用寿命，特别是在车速较高或波磨较严重的线路，建议弹条安装时安装扭矩不超过300 N·m。

Abstract:

To effectively evaluate and predict the fatigue life of the W300-1 fastening clip during service， a finite element model was established， by considering the elastic-plastic mechanical properties and nonlinear contact relations of the clip. The strain characteristics of the clip at different installation loads were analyzed， and the test results were verified based on digital image correlation （DIC） technology. The fatigue life of the clip was calculated by applying the fatigue load in combination with the strain-life curve based on the actual measurement wheel-rail force time-history curve of Beijing-Shanghai High Speed Railway. The influence of installation torque， fatigue cycle load amplitude and the matching relations between them （the stress ratio） on the fatigue life of the clip was analyzed. The results show that the lowest fatigue life is found at the heel of the clip， and plastic deformation occurs no matter in a state of slightly under-tightening installation， normal installation， or over-tightening installation. The fatigue life decreases with the increase of installation torque and fatigue load amplitude， but it is linearly proportional to the stress ratio at the dangerous point of the clip. Therefore， to ensure the actual service life of the clip， especially in high speed or serious corrugation lines， it is recommended that the installation torque of the clip should not exceed 300 N·m.