Vibration Behaviour And Damage Analysis Of High Speed Bogie Frame Under Wheel Polygonal Excitations

As a popular mode of transportation,railway transportation occupies an important position in the construction of national infrastructure.With the development of high-speed and lightweight of railway vehicles,its’ dynamic problems in the operation process are also increasingly prominent.As a typical service issue,the wheel polygon will generate highfrequency excitation through wheel-rail contact,which can intensify the vibration of bogies,reduce the fatigue longevity and worsen the dynamic performances of vehicles.Therefore,the thesis analyzed the vibration and fatigue damage for high-speed bogie frame under wheel polygonal excitations through the combination of simulation and bench test,the main work is as follows:(1)Firstly,for a certain type of EMU in China,the structural modal and frequency of the bogie frame and wheelset were determined by finite element analysis,then the rigid-flexible coupling dynamic model of vehicle system was established considering flexible wheelset and frame.Based on the small roller high-frequency excitation test bench,the test was carried out to compare with the simulation results,which verified the feasibility of the simulation model,and the modal shape of the frame at 577 Hz of the wheel polygonal excitation was obtained.(2)Secondly,based on the bench test,the research on the vibration and dynamic stress of the bogie frame under the small roller polygonal excitations was conducted,the vibration response was acquired through the test,and the equivalent stress of the frame was analyzed using the dynamic stress data in the test.(3)Furthermore,based on fatigue damage theory,the process of fatigue life assessment of components by time domain and frequency domain methods was given,and the fatigue damage assessment of dynamic stress data in the bench test was carried out through these two methods.Also,the damage degree of each part of the frame was compared and analyzed.(4)Finally,based on the rigid-flexible coupling dynamic model,the vibration responses of the bogie frame under single and double wheel polygonal excitations were calculated,and the influences of the phase difference,vehicle speed,polygon order and amplitude on the vibration acceleration and load state of the frame were compared and analyzed.