重载铁路扣件弹条裂纹扩展与寿命预测  

Crack extension and life prediction of fastening spring clip in heavy-haul railways

作　　者：王煜轩 王志丰[1] 聂少锋[2] 王亚琼[1] WANG Yu-xuan;WANG Zhi-feng;NIE Shao-feng;WANG Ya-qiong(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;School of Civil Engineering,Chang'an University,Xi'an 710061,Shaanxi,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]长安大学建筑工程学院,陕西西安710061

出　　处：《交通运输工程学报》2025年第1期221-233,共13页Journal of Traffic and Transportation Engineering

基　　金：国家重点研发计划(2021YFF0501101);国家自然科学基金项目(52478384);陕西省创新能力支撑计划项目(2023-CX-TD-35);陕西省秦创原“科学家+工程师”队伍建设项目(2023KXJ-159)。

摘　　要：为研究重载铁路有砟轨道扣件系统中的弹条疲劳寿命,建立了车-轨-基础耦合动力分析模型与扣件系统分析模型;计算了不同轴质量情况下扣件处轨底位移时程曲线,并将其作为位移荷载施加于正常安装状态下的扣件系统模型中来分析弹条在服役状态下的力学特性;基于应变-寿命曲线、累计损伤理论与裂纹扩展理论,分析了弹条裂纹扩展过程中的受力情况及轴质量对弹条疲劳寿命的影响。研究结果表明:弹条在25 kN的螺栓预压力情况下达到正常安装状态,弹条中肢垂向位移为10.2 mm,扣压力为10.1 kN,且应力最大处位于弹条后弯肢处;轴质量的增加通过改变弹条的应力比来影响疲劳裂纹萌生寿命,随着轴质量的增加,弹条材料属性对萌生寿命的影响比重降低;轴质量在由27 t增加至40 t时疲劳裂纹萌生寿命逐渐减少,40 t轴质量时疲劳裂纹萌生寿命约为128万次,较35、30 t轴质量时分别减少约63%和95%,同时寿命的降低速率也逐渐变缓;裂纹在弹条内部扩展时方向会产生扭转,裂纹前端应力向四周呈放射性衰减,同时应力方向朝两侧呈张拉状;弹条裂纹在开裂初期扩展速率较慢,随着深度增加,扩展速率不断加快;弹条的疲劳裂纹扩展寿命与累计通过总质量随着轴质量的增大而减小,且裂纹扩展寿命低于裂纹萌生寿命。The coupled vehicle-track-foundation dynamic analysis model and the fastening system analysis model were established to study the fatigue life of the spring clip in the fastening systems of ballasted tracks in heavy-haul railways.The time curves of the rail bottom displacement at the fastenings under different axle loads were calculated.The curves were applied as displacement loads in the fastening system model under normal installation conditions to analyze the mechanical behavior of the spring clip under service conditions.Based on the strain-life curve,cumulative damage theory,and crack extension theory,the stress of the spring clip during crack extension and the influence of axle load on the fatigue life of the spring clip were analyzed.Research results show that the spring clip reaches the normal installation state under 25 kN bolt preload.The vertical displacement of the middle limb of the spring clip is 10.2 mm,the clamping force is 10.1 kN,and the maximum stress is located at the rear curved limb of the spring clip.The increase in axle load affects the fatigue crack initiation life by changing the stress ratio of the spring clip.With the increase in axle load,the influence of the material properties of the spring clip on the initiation life decreases in proportion.The fatigue crack initiation life decreases progressively as the axle load increases from 27 t to 40 t.When the axle load is 40 t,the fatigue crack initiation life is about 1.28 million times,approximately 63%and 95%less than that at axle loads of 35 t and 30 t,respectively.Meanwhile,the rate of decrease of the fatigue crack initiation life is slowing down.The direction of the crack is twisted as it expands inside the spring clip.The stress at the front of the crack decays radially in the surrounding direction,while the stress direction is tensile towards the sides.The extension rate of spring clip cracks is slow at the beginning of cracking and keeps accelerating with increasing depth.The fatigue crack extension life and cumulative total passin

关 键 词：铁道工程 扣件弹条 疲劳损伤 疲劳寿命 裂纹扩展 裂纹尖端特性 

分 类 号：U213.5[交通运输工程—道路与铁道工程]