Chengshi guidao jiaotong yanjiu (Aug 2024)
Fatigue Analysis of Urban Rail Transit Vehicles Bogies Based on Frequency Domain Features
Abstract
Objective As a key structure for carrying the vehicle, the abnormal vibration of bogies has a direct impact on the service performance of rail transit trains. Therefore, it is necessary to conduct in-depth research on the fatigue of vehicle bogies. Method In response to the abnormal bogie vibration on a certain urban rail transit train, a main line passenger tracking test is conducted to analyze the dynamic stress in the key areas for the testing vehicle. Combined with the elastic mode of bogie frame, the frame vibration and main frequency of wheel-rail excitation under different track types are compared and studied. Result & Conclusion The equivalent stress (σaeq) of 17 measuring points on train bogie frame exceeds the limit of 70 MPa before wheel reprofiling, while only one measuring point exceeds the limit after wheel reprofiling. Therefore, wheel off roundness has a significant impact on the dynamic stress of the frame. The main frequency of the frame dynamic stress signal both before and after wheel reprofiling is 59 Hz in the low-frequency range, and the main frequency energy still exists after wheel reprofiling, indicating that its correlation with train running speed and wheel off roundness is relatively small. The main frequency of dynamic stress signal is above 700 Hz in the high-frequency range. Since the high-frequency σaeq is mainly within 25 MPa, its contribution to the damage of bogie frame is very small. This type of bogie frame has an elastic mode with a frequency of about 59 Hz, where motor and side beam nod in the opposite direction. The frequency of this elastic mode is consistent with the main frequency of the dynamic stress signal of vehicle dynamic stress measurement points on three track types: long sleeper integrated track bed+ZX-2 fastener, short sleeper integrated track bed+ZX-2 fastener, and floating plate track bed (high-end steel)+ZX-2 fastener. However, this main frequency does not exist on other track types, indicating that the elastic mode of the frame is excited on some track types, causing excessive fatigue damage values. The vertical vibration main frequencies of the vehicle axle box on this line are 60.5 Hz and 37.0 Hz respectively, of which 60.5 Hz is mainly generated by the coupling effect between the vehicle and the track, and 37.0 Hz has a certain correlation with the vibration damping fasteners. Therefore, the combination of track bed and fastener types has a significant impact on the wheel rail vibration.
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