Experimental Investigation On The High-frequency Vibration And Fatigue Of High-speed Bogies

In recent years,with the development of high-speed railroads in China,more and more high-speed trains have been put into operation,and the problems such as wheel polygons are more prominent,resulting in high-frequency vibration of high-speed trains during actual passenger operation,which aggravates the vibration of vehicle components and increases the stress of key components,affecting the service life of vehicles.In the thesis,we take the bogie of a certain type of rolling stock as the research object,based on the single wheel pair highfrequency excitation test bench test,the working mode identification of two key local structures of the bogie,analysis of high-frequency vibration transmission characteristics of high-speed train bogie under high-frequency excitation,and high-frequency vibration fatigue damage response analysis of two typical local structures of the frame.The main contents of this paper are as follows.(1)Based on the single-wheel pair high-frequency excitation test bench test,the acceleration time domain signals and stress time domain signals of each structure of highspeed train bogie(frame end,brake boom,frame as a whole and swivel arm positioning seat)are obtained,and two key local structures of the frame(frame end and brake boom)are obtained through the analysis of acceleration and stress time domain signals of each part,and their working modes are identified.A total of 5 working modes are obtained for the frame end,among which the stress is the highest at 570 Hz excitation,and the corresponding vibration pattern is the torsional motion of the frame end;8 working modes are obtained for the brake boom,among which the stress is the highest at 95 Hz excitation,and the corresponding vibration pattern is the lateral swing of the brake boom.(2)The high frequency vibration transmission characteristics of the high-speed bogie are studied with reference to the forced vibration theory of the single degree of freedom system,and the acceleration frequency response characteristic curves and stress frequency response characteristic curves of the two key local structures(frame end and brake boom)are obtained.The damping ratio is solved based on the half power point method and the acceleration frequency response curve.The resonance bandwidth of acceleration and stress of the frame end is 12 Hz,and the damping ratio is 1.1%;the resonance bandwidth of acceleration and stress of the brake boom is 1 Hz,and the damping ratio is 0.5%.(3)Based on the fatigue damage theory,and combined with the frame end and brake boom stress frequency response characteristics curve,the two key local structure in the unit vibration input stress magnitude,and obtain the frame end and brake boom equal amplitude axle box vibration 50 g input,different frequency corresponding to the stress duration of the damage results under the equal amplitude time,and according to the damage results to obtain the structure of the damage-frequency curve.curve.The damage caused by the resonance of the frame end at 570 Hz was 0.34,while the damage caused by other frequencies was much less than 0.34;the damage caused by the resonance of the brake boom at 95 Hz was 17,which was much more than 1,but the damage caused by other frequencies was about 0.01,which did not cause much damage to the structure.The damage results are compared and analyzed,and design recommendations for the damping ratio in the design process of the structure are proposed.If the structural damping ratio is large,the damping ratio should be further increased during the redesign to reduce the resonance peak and lower the damage value;if the structural damping ratio is smaller,the structural damping ratio should be further reduced during the redesign to narrow the resonance range and make the probability of resonance further smaller.