高速列车车轮磨耗预测仿真

为了研究高速列车车轮磨耗问题,建立了车辆多体系统动力学和车轮磨耗耦合模型.模型中考虑了车辆系统悬挂非线性?轮轨接触几何非线性和轮轨蠕滑力非线性.采用数值仿真方法研究车轮型面的磨耗分布和发展.考虑车辆通过一条由直线和不同曲线组成的典型线路,通过动力学仿真计算轮轨接触情况,采用FASTSIM计算轮轨接触斑上车轮磨耗量,进行车轮型面磨耗量的累积和型面外形更新,然后再进入下一个磨耗循环的计算.通过比较分析,选择车轮型面垂直磨耗0.1mm为型面更新的条件,分别采用Archard磨耗模型?基于摩擦功的磨耗模型和基于磨耗指数的磨耗模型来预测车轮型面磨耗发展情况.并与测量得到的车辆实际线路运行中车轮磨耗量进行了比较.结果表明,仿真得到的车轮型面磨耗发展情况和实际测量结果趋势相同,其中基于磨耗功和磨耗指数模型的计算结果接近,而Archard模型算得的轮缘磨耗相对较大.因此,可以根据具体线路有针对性地选择磨耗模型,通过仿真方法预测车轮型面的磨耗,为高速列车的安全可靠运行提供指导.     

测定概率疲劳长裂纹扩展门槛值的新方法

提出了合理测定随机疲劳长裂纹扩展门槛值的"局部概率Paris关系法"·　揭示了常规法不能保证各试样门槛值数据处于相同扩展率水平,测定结果不尽合理的缺陷·　以Paris_Erdogan方程描述门槛值附近局部试验数据,考虑数据分散性规律和试样数量两方面的影响,在应力强度因子服从对数正态分布下建立了包含存活概率和置信度的局部概率关系模型,以可接受临界扩展率对应概率因子为依据测定概率门槛值·　LZ50钢车轴试验数据分析验证了方法的合理性和有效性·     

NEW METHOD FOR MEASURING RANDOM THRESHOLDS OF LONG FATIGUE CRACK PROPAGATION

A so-called "local probabilistic Paris relation method" was presented for measuring the random thresholds of long fatigue crack propagation. A check was made to the conventional method, in which the thresholds were measured statistically and directly by the test data. It was revealed that this method was not reasonable because the test data have seldom a unified level of crack growth rates. Differently,in the presented method the Paris-Erdogan equation was applied to model the local test data around the thresholds. Local probabilistic relations with both the survival probability and the confidence were established on a lognormal distribution of the stress density factors. And then, the probabilistic thresholds were derived from the probabilistic factors with a given critical level of growth rate. An analysis on the test data of LZ50 axle steel for the Chinese railway vehicles verifies that the present method is feasible and available.     

PROBABILISTIC MODELS FOR LONG FATIGUE CRACK GROWTH RATES OF LZ50 AXLE STEEL

IntroductionStudy on the model of fatigue crack growth rate (da/dN) and measurement of theprobabilistic curves of the model are a basis of the fatigue damage tolerate design and theprobabilistic safety assessment. Some benefit efforts have been made in th…     

LZ50车轴钢疲劳长裂纹扩展的概率模型

试验研究了随机疲劳长裂纹扩展率概率模型.首先发展了考虑平均应力影响和低应力强度因子范围趋于门槛值现象的扩展率方程.进而提出了同时考虑试验数据分散性规律与样本数量对概率评价影响的概率模型,模型参量由线性回归法结合极大似然统计分析原理测定.LZ50钢的试验数据分析,验证了方法的有效性与实用性.