纵向冲击下高速列车车体承载极限数值模拟

进行了高速列车车体6005A-T6、6082A-T6铝合金的静态拉伸和动态压缩试验，识别了0.001~2 500 s-1应变率范围内2种铝合金的材料应变率效应，建立了对应的Johnson-Cook本构模型；构建了高速列车典型车辆的显式动力分析模型，完成了刚性墙冲击车体过程仿真，研究了车钩稳态载荷、冲击速度、加载方式对车体承载极限的影响；分析了高速列车一号车和二号车车体在冲击载荷下的变形演化，通过应力变化临界点确定了车体的承载极限，并对列车在更高能量配置模式下的车体承载性能进行了验证。研究结果表明:在0.001~2 500 s-1应变率范围内，6005A-T6和6082A-T6铝合金应变率敏感系数分别为2.9×10-3和8.5×10-3，应变率效应不明显；纵向动态冲击载荷下，应变率强化对铝合金车体结构承载力影响不明显，惯性效应是其承载能力高于静态极限的主要原因；纵向冲击载荷从车钩位置传递时，一号车和二号车车体的动态承载力水平显著高于车体许用静态压缩载荷；冲击载荷下的车体结构承载力可为高速列车碰撞各界面能量分布问题中吸能元件平台力取值提供上界；可适当考虑提高车体许用压缩载荷以扩大列车端部吸能部件力学参数设计域，以满足更苛刻需求下的列车被动安全性能。 

Numerical simulation of bearing capacity of carbody for high-speed train subjected to longitudinal impact

The static tension and dynamic compression experiments of the aluminum alloy 6005A-T6 and 6082A-T6 used in the carbody of high-speed train were carried out, their strain rate effects within the strain rate range of 0.001-2 500 s-1 were identified, and the corresponding Johnson-Cook constitutive model was established. An explicit dynamic analysis model for the typical vehicle of high-speed train was constructed, the process of the carbody impacted by a rigid wall was simulated, and the influence of coupler stable force, impact speed, and loading condition on the bearing capacity of the carbody was investigated. The deformation evolution of the carbodies 1 and 2 for the high-speed train subjected to the impact load was analyzed, the bearing capacity of the carbody was determined by finding the critical point of stress change, and the crashworthiness of the train configured with a higher energy mode was analyzed for the performance verification. Research results indicate that the strain rate sensitivity coefficients of the 6005A-T6 and 6082A-T6 aluminum alloys are 2.9×10-3and 8.5×10-3 within the strain rate range of 0.001-2 500 s-1, respectively, so their strain rate effects are not obvious. Under the axial dynamic impact load, the strengthening effect of the strain rate has no obvious effect on the bearing capacity of the aluminum alloy carbody structure, and the inertial effect is the main reason that its bearing capacity is higher than the static limit. When the longitudinal impact load is transmitted at the coupler position, the dynamic bearing capacity limitations of the carbodies 1 and 2 are obviously higher than the maximum allowable value under the static compression. The bearing capacity of the carbody structure under the impact load can provide an upper bound for the platform force of the energy absorbing element used in the interfacial energy distribution problem of the high-speed train collision. It is recommended to enlarge the mechanical parameters' design domains of the energy absorbing components by appropriately increasing the allowable load, meeting the passive safety performance of the train considering more severe requirements. 1 tab, 22 figs, 31 refs.