Identification of Excitation Force for Under-Chassis Equipment of Railway Vehicles in Frequency Domain

Abstract

The excitation force of under-chassis active equipment of railway vehicles has a significant impact on the flexible vibration of the car body. Mastering the excitation force of equipment can control the vehicle body vibration more comprehensively. To identify the excitation force of under-chassis equipment of railway vehicles, four frequency-based force identification methods such as least square method and Tikhonov regularization methods based on L-Curve, ordinary cross-validation, and generalized cross-validation respectively, are studied. Laboratory test shows the effectiveness of the above identification methods. A plate model is used to analyze the influence of the measuring positions and measuring noise on the identification accuracy of different types of excitation forces. It is found that it is a suitable method to determine the optimal combination of measuring points according to the optimal condition number criterion. Based on the finite element model of the car body with under-chassis equipment, the excitation force of the under-chassis equipment is identified, and the validity of the optimal condition number criterion is verified. In addition, the results show that when the frequency response function and the responses of measuring points are disturbed by noise, the above methods show different robustness to the models with different degrees of complexity. The equipment structure of railway vehicles is complicated, which is easy to be disturbed by noise in the actual test, and the signal-to-noise ratio is small. Therefore, it may be appropriate to choose Tikhonov regularization based on the L-Curve.