基于多维多点虚拟激励法对转向架构架随机振动疲劳寿命预测

Fatigue life prediction of bogie frames under random vibration based on the multi-dimensional and multi-support pseudo excitation method

针对轨道车辆运行中受到来自轨道不平顺的多维多点随机激励,采用多维多点虚拟激励法求解其的动力响应。建立某地铁列车的车体、构架、轮对之间相互作用的有限元模型,通过在有限元模型激励处置入大质量,并将推导出的多维多点力功率谱密度矩阵施加于大质量上,运用绝对位移直接求解运动方程,再利用三区间法对转向架构架焊缝疲劳薄弱位置进行寿命预测。计算结果显示,构架的刚性沉浮、横摆、点头模态与弹性扭转模态对其疲劳寿命有较大的影响;研究过程表明,基于多维多点虚拟激励法的振动疲劳计算方法避免了传统虚拟激励法求解拟静态矩阵的繁琐,从而能更高效、快速地求解出车辆运行时的动力响应,同时可为转向架构架从刚度协调的角度提高抗疲劳能力及优化设计提供一种新的途径。

In order to analyze the dynamic responses of railway vehicles under the random excitation from track irregularity,a multi-dimensional and multi-support pseudo excitation method was proposed.The finite model of a metro train considering the interaction among the car body,frame and wheelset was established,in which a large mass was set at the excitation place and subjected to the excitation of the derived multi-dimensional and multi-support force power spectral density matrix.Then the motion equations of railway vehicles were directly solved by using the absolute displacement method.Finally,the three-interval method was used to predict the fatigue life of bogie frame welds.The results show that the rigid modes of bounce,yaw,pitch and the elastic mode of torsion of the bogie frame have great influence on its fatigue life.The results indicate that the vibration fatigue calculation method based on multi-dimensional and multi-support pseudo excitation method can avoid the tedious calculation for the quasi-static matrix by the traditional virtual excitation method,and solve the dynamic responses of vehicles more efficiently and quickly.The study provides a new way for improving the fatigue resistance capability and the optimum design of bogie frames from the aspect of stiffness coordination.