Research on resonance mechanism of articulated train car body based on modal vibration extraction method

The physical vibration of railway train car body is the superposition of various modal vibrations of the car body. In this study, a modal vibration extraction method (MVEM) based on singular value decomposition and least squares fitting is proposed to decouple the physical vibration of the car body into modal vibrations. Then, from the perspective of modal vibration energy, the calculation method of modal vibration contribution (MVC) is proposed, and the main participating modes of the car body are tracked in the process of train operation, and the resonance mechanism of articulated train car body is analyzed based on them. The results show that the end constraint forms of the head car body and the middle car body of the articulated train are different, resulting in the influence of the velocity on the yaw vibration energy of the head car body is obviously greater than that of the middle car body; due to the articulated effect between the train car bodies, the yaw motion of each car body is aggravated, which further worsens the lateral ride quality of the car body floor above the bogie; with the increase of train running speed, the dominant modes contributing to car body vibration change from rigid modes to elastic modes. The first-order vertical bending mode, first-order lateral bending mode, and diamond-shaped deformation mode contribute greatly to car body vibration, and there is no resonance between them and bogie frame. In fact, geometric filtering is the reason for the resonance of the car body. Moreover, the geometric filtering phenomenon occurs in the vehicle with symmetric structure (middle vehicle) and the vehicle with incomplete symmetric structure (head vehicle), and the geometric filtering phenomenon also exists in the vertical and lateral vibration of the vehicle.