【作者】 田军；

【导师】 李强；

【作者基本信息】 北京交通大学 ， 车辆工程， 2014， 博士

【摘要】 840D车轮曾是我国运用数量最多的货车车轮,在役数量一度达320万片之多。840D车轮辐板孔疲劳裂纹曾是货车车轮故障的主要形式,且曾发生过多起因辐板孔裂纹导致的行车事故,对铁路运输安全带来严重威胁。本文根据840D车轮辐板孔裂纹调查统计数据分析、轮轨机械载荷和制动热负荷下的裂纹尖端应力和强度因子仿真计算等结果,对裂纹成因、扩展规律、剩余寿命、容限尺寸及运用安全性进行了系统分析研究,主要研究工作包括以下几个方面：1裂纹成因及其扩展规律的试验研究对典型辐板孔裂纹的宏、微观形貌及金相组织进行分析,确定裂纹的性质、产生原因及扩展模式；对辐板裂纹萌生寿命进行了试验研究。2裂纹形成和扩展规律的仿真研究根据车轮运用中的轮轨机械载荷和制动热负荷条件,采用有限元法进行辐板孔应力应变和裂纹应力强度因子计算,提出轮轨机械载荷和制动热负荷组合作用下的应力叠加方法,研究并建立考虑踏面磨耗量、辐板孔位置等多参数影响的裂纹形成寿命和剩余寿命预测模型,计算出典型制动工况和大秦线全程运用条件下裂纹的形成寿命、裂纹扩展剩余寿命,进而综合分析导致裂纹形成和扩展的载荷条件并探讨踏面磨耗量、辐板孔位等几何因素对裂纹形成和扩展的影响机制。3复合型裂纹应力强度因子仿真及断裂准则研究采用1/4节点位移法及子模型技术,建立车轮辐板孔裂纹的三维有限元模型,完成了复合型裂纹应力强度因子仿真并得到不同裂纹尺度下应力强度因子的变化规律；建立辐板孔复合型裂纹的断裂准则,预测了裂纹失稳扩展的临界尺寸。4对调查样本数据的统计分析利用长期跟踪大秦线带裂纹车轮试验数据和铁路货车技术管理信息系统(HMIS)记录的数据,根据在全路7家车辆修造单位现场调研取得的20316个辐板孔车轮样本数据,分析辐板孔裂纹的分布规律,得出裂纹发生率与使用时间、轮辋厚度、孔偏位置的关系;采用二参数威布尔分布,建立辐板孔裂纹萌生寿命与扩展速率的概率模型,计算不同可靠度下的裂纹萌生寿命与扩展速率并进而推断840D车轮的安全使用条件。5辐板孔裂纹研究的工程化应用在大秦线实际制动运用工况的基础上,补充了直线制动工况和曲线制动工况,分析了踏面制动热输入对车轮强度的影响,为UIC510-5标准车轮强度评定方法进行平均应力的修正提供了依据,初步尝试了货车车轮辐板结构优化设计工作,并对轮辋裂纹扩展研究进行了可行性分析。更多还原

【Abstract】 The type840D wheel used to be the largest amount of wagon wheels in service, with its number almost up to3.2million. The fatigue crack around the plate hole of840D wheel was the main form of wagon wheel malfunctions, which resulted in a couple of operation accidents, seriously threats the railway transportation safety.Based on the analysis to abundant investigation and statistic data of the crack around plate hole of840D wheel, plus the simulation to stress and crack intensity factor of wheel-rail load and heat load during braking, this thesis studies the crack initiation condition, crack propagation law, residual life, crackallowance size and serving safety. The primary work and remarks of this thesis are as follows:1. Experimental research on crack initiation and propagation lawThe analysis of macroscopic and microscopic fracture pattern and metallographic character were processed to determine the crack initiation mechanism and propagation model; then crack initiation life of spoke plate were studied.2. Simulation research on crack initiation and propagation lawThe stress and strain of plate hole and crack stress intensity factor have been analyzed by finite element method according to the wheel-rail mechanical load and heat load during braking. The stress superimposing method was put forward for solving the stress superimposition under mechanical and thermal loads. The model was set up to study influence of rim wear and plate hole offset on crack initiation life and residual life, then the crack forming life, expanding life and residual life are calculated under braking condition and other typical conditions on the Datong-Qinhuangdao Railway. Based on this, the load cause of crack forming and expanding was analyzed, the influence mechanism of rim wear, position of plate hole and other geometrical factors on crack forming and expanding were discussed.3. Simulation of complex crack stress intensity factor and study on breaking rulesThe3D FE model of crack around plate hole was set up applying the1/4node displacement method and the sub-model technique. Based on study on complex crack intensity factor, the stress intensity factor variation rules under different crack dimensions were simulated, then breaking rules of complex crack around plate hole were established, critical dimensions of crack expanding was predicted.4. Statistical analysis on the sample data According to the sample data both in tracking observation of the operating wheels on the Datong-Qinhuangdao Railway and the management information system of railway wagon (HMIS), which was equal to20316, obtained from7wagon plants. This thesis draw relationships among crack ratio with employ time, rim thickness and hole offset. The probability model that can be used to predict the crack initiation lifespan and expansion velocity was built with the adoption of a2-parameter Weibull distribution, then the crack initiation lifespan and expansion velocity under different reliability were analyzed and the safety states of operating840D wheels could thus be inferred.5. The engineering application of the plate hole crack studyBased on real braking conditions on the Datong-Qinhuangdao Railway, braking conditions in straight line and curve line were complementary, the influence on wheel strength was simulated by inputting tread braking heat This thesis made a correction to the UIC510-5wheel strength assessment using mean stress method. The structure optimization of wagon wheel spokes and the feasibility analysis to the rim crack expanding study are also put out.更多还原