基于Cowper-Symonds本构模型铁路车轮扁疤激发的轮轨冲击仿真分析

Finite Element Simulation of the Flat-Induced Wheel-Rail Impact Based on the Cowper-Symonds Empirical Model

轮轨关系是高速铁路工程领域最重要的研究课题之一,车轮扁疤作为一种主要的轮轨失效形式,严重影响了高速列车运行的平稳性和安全性。利用Hypermesh软件建立了带有扁疤的三维轮轨滚动接触模型,并基于轮、轨钢Cowper-Symonds本构模型,采用LS-DYNA3D显式算法进行了相应的有限元仿真分析,重点研究了车速、扁疤长度和轴重对轮轨冲击响应的影响。仿真结果表明:车轮扁疤缺陷引起的最大轮轨垂向冲击力显著大于相应的准静态垂向载荷,最大von Mises等效应力和最大等效塑性应变通常发生在轮轨接触表面;轮、轨钢的应变率效应对轮轨垂向冲击力没有影响,但由于应变率的强化效应,与不计应变率效应的结果相比,基于Cowper-Symonds模型得到的最大von Mises等效应力明显增大,而最大等效塑性应变略有降低;车速、扁疤长度和轴重对轮轨冲击响应均有显著的影响。研究结果可为轮轨系统的安全性设计与评估提供技术支持。

The wheel-rail interaction is a major concern in research for high-speed rail transport. As a main type of wheel/rail failure, the wheel flats exert serious restriction on the stability and safety of high-speed trains. In this study, a three-dimensional wheel-rail rolling contact model with a flat was built using the Hypermesh software,and the corresponding finite element simulation was conducted, based on the Cowper-Symonds empirical model, using the LS-DYNA 3D explicit algorithm. Influences of the train speed, flat length and axle load on the wheel-rail impact response were discussed, respectively. The simulation results indicate that the maximum vertical wheel-rail impact force is significantly larger than the corresponding static axle load due to the presence of a wheel flat,and the maximum von-Mises equivalent stress and maximum equivalent plastic strain are observed on the wheel-rail contact surface. The strain rate-dependent constitutive parameters of the wheel/rail steels have no influence on the maximum vertical wheel-rail impact force- however, due to the hardening effect of the strain rate, the maximum von-Mises equivalent stress obtained from the Cowper-Symonds model is obviously larger than that derived from the rate-independent one, while the maximum equivalent plastic strain derived from the Cowper-Symonds model is smaller than that under rate- independent one. Besides, the wheel-rail impact response is demonstrated to be sensitive to the train speed, flat length and axle load. These findings can provide technological supports for safety design and assessment of the wheel-rail system.