高速铁路无缝钢轨断缝瞬态冲击行为分析

无缝线路钢轨焊缝及其热影响区在温度力作用下可能发生钢轨折断形成断缝. 为了研究钢轨折断对列车运营安全的影响，对轮轨接触受力特性及其材料高频动态响应进行了分析. 首先，建立了ANSYS/LSDYNA三维轮轨瞬态滚动接触有限元模型；然后，根据不同速度轮轨力时域响应规律，选择了合适的模型计算工况，并且通过计算轮轨接触受力特性和材料高频动态响应，分析了车轮跨越断缝的安全问题；最后，通过小波变换获取了车轮跨越断缝时轮轨力的频域分布. 结果表明:断缝处轮轨高频冲击力峰值随断缝长度变化先减小后增大，转折点处断缝长度与行车速度负相关；车轮通过断缝时，钢轨最大剪切应力超过材料破坏极限，易导致钢轨材料脆断；轮轨力时频图中存在两个特殊频率成分，分别对应高频冲击荷载（1 500 Hz左右）及二次冲击荷载（450 Hz左右），断缝长度对轮轨力频域分布影响较小. 

Transient Impact Behavior Analysis of Rail Broken Gap on High-Speed Continuous Welded Rail

The rail of seamless track may break and form a broken gap at the weld and its heat affected zone under temperature force. In order to study the influence of rail broken gap on train operation, the wheel-rail contact force characteristics and the high-frequency dynamic response of the material is analyzed. First, the ANSYS/LSDYNA three-dimensional wheel-rail transient rolling contact finite element model was established; then, according to the time-domain response of wheel-rail forces at different speeds, the appropriate calculation conditions are selected, and the safety issue in the case of the wheel crossing the broken gap is analyzed by calculating the wheel-rail contact force and the high-frequency dynamic response of the material; finally, when the wheel crosses the gap, the frequency-domain distribution of the wheel-rail force is obtained by wavelet transform. The results show that the peak value of the high-frequency impact force decreases at first and then increases as the length of the rail broken gap increases. The length of the broken gap at the turning point is inversely correlated to the train speed; when the wheel passes through the gap, the maximum shear stress of the rail exceeds the material failure limit, which may cause the brittle fracture of the rail material; there are two special frequency components in the time-frequency diagram of the wheel-rail force, which respectively correspond to the high-frequency impact load (about 1 500 Hz) and secondary impact load (about 450 Hz); the gap length has little effect on the frequency-domain distribution of the wheel-rail force.