基于应变模态的轨道车辆车体应力计算方法

Stress Calculation Method of Railway Vehicle Car Body based on Strain Mode

在轨道车辆结构设计中,分析结构在动载作用下的应力状态是进行强度设计和疲劳寿命估计的关键,但应力不能直接进行测量,一般通过位移模态分析方法建立车体结构位移响应模型,再通过位移与应变的相互关系得到车体的应变响应,进而得到应力状态。由于从位移到应变是微分过程,位移的变动将会得到放大,从而带来误差。利用位移模态理论推导出应变模态理论及其性质,通过车体有限元模型的位移模态及应变模态的仿真分析表明,相对于位移模态,应变模态对损伤更为敏感。利用模态叠加方法可获得车体应变、应力时间历程,为疲劳寿命预测及载荷谱研究提供依据。

In the structure design of rail vehicle, the key of the strength design and fatigue life estimation is to analysis the stress state of the structure under the dynamic load.However,the stress cannot be measured directly.Generally,the displacement response model of the body structure is established by the displacement modal analysis method,and then the strain response of the vehicle body is obtained by the relationship between the displacement and the strain,and thus the stress state is obtained.Since the displacement to the strain is a differential process,the variation of displacement will be magnified and the errors will be result in.Strain modal theory and its properties are derived from displacement modal theory.The results show that it is more sensitive for strain modal to the damage than displacement modal through the simulation analysis of the displacement mode and strain mode of the car body finite element model.the mode superposition method can be used to obtained the strain and stress time history of car body,which can provide a basis for fatigue life prediction and load spectrum research.