车体振动模态对疲劳强度的影响分析

铁路运输车辆不断朝着高速以及轻量化方向发展,车体承受着复杂的交变载荷,极大地增加了车体结构疲劳断裂的风险。为探究车体结构振动对车辆结构安全性的影响,利用ANSYS Workbench进行车体模态仿真计算。结合服役环境下动车组车体运行模态测试数据,提取出车体1阶菱形(8~9 Hz)、1阶垂弯(12~13 Hz)、1阶横弯(15~16 Hz)及1阶扭转(17~18 Hz)模态频率,对车体有限元模型进行对比修正。利用雨流计数法对部分实测载荷谱数据谱进行处理,得到载荷谱雨流计数矩阵。在模态分析的基础上进行谐响应分析,得到上述不同模态频段范围内的频率响应函数,结合nCode疲劳仿真软件对车体疲劳强度进行仿真计算,得到不同频段范围内车体的疲劳损伤;采用Miner线性累积疲劳损伤理论对仿真计算结果进行疲劳损伤评估,结果表明:车体1阶菱形模态(8~9 Hz)附近频段对车体造成的损伤最大,其损伤位置在车钩与枕梁交接处附近。

Analysis of the Influence of Vehicle Vibration Mode on Fatigue Strength

Railway transportation vehicles are developing towards high speed and light weight. The vehicle body bears complex alternating loads, which greatly increases the risk of fatigue fracture of the vehicle body structure. In order to explore the influence of vehicle body structure vibration on the safety of vehicle structure, ANSYS Workbench was used to simulate the vehicle body mode. Combined with the modal test data of the EMU body in the service environment, the first order diamond (8~9 Hz), first order vertical bend (12~13 Hz), first order transverse bend (15~16 Hz) and first order torsion (17~18 Hz) model frequencies were extracted, and the vehicle finite element model was compared and modified. The measured data of the measured load spectrum were processed by using the rain flow counting method, and the load spectrum rain flow counting matrix was obtained. Based on the modal analysis, the harmonic response analysis was carried out, and the frequency response functions in the above different modal frequency ranges were obtained. The nCode fatigue simulation software was used to simulate the fatigue strength of the vehicle body, and the fatigue damage of the vehicle body in different frequency range was obtained. Miner linear cumulative fatigue damage theory was used to evaluate the fatigue damage of vehicle body. The results show that the frequency band near the first order diamond shaped mode (8~9 Hz) of the vehicle body causes the most damage to the vehicle body, and the damage location is near the intersection of the vehicle hook and bolsters.