| Nowadays,the high-speed railway industry in our country is developing rapidly.With the improvement of the operating speed,the safety and reliability of the high-speed train are more prominent.The wheel polygon is a big problem that affects the safety of high-speed trains.Therefore,in this paper,the vehicle vibration response and dynamic response of the CRH2A high speed EMU under wheel polygon was studied,the fatigue life of the frame was calculated under wheel polygon.The specific research contents are as follows:(1)The rigid vehicle dynamics simulation model of CRH2A high speed EMU was established by using Simpack software.Then the rigid flexible coupling dynamic model was established by using ANSYS substructure analysis module and Simpack flexible body module,the vehicle system model of wheel,axle box and frame were made of elastomer.(2)The resonance of natural frequencies of wheelset and frame with the passing frequency of the wheel polygon at a speed of 50-300km/h was studied.Through the modal analysis of the bogie,it was found that when the passing frequency of the wheel polygon is close to the natural frequency of the frame and wheelset,caused the frame and wheelset to vibrate abnormally.It is suggested that high-speed train with wheel polygon at a variable speed to avoid resonance of the wheel polygon passing frequency and the bogie’s natural modal frequency at a certain speed for a long time.(3)The simulation studied the vehicle’s dynamic response at different speed,different amplitude and different order of wheel polygon.The study found that wheel polygon has little effect on the derailment coefficient and ride comfort;The amplitude of the vertical force of the wheel/rail is positively related to the amplitude of the velocity and wheel polygon;The maximum wheel/rail vertical force increases with increasing wheel polygon order;Wheel load reduction rate is proportional to the wheel polygon’s amplitude;The critical speed decreases as the order of the wheel polygon increases According to the criteria of wheel load reduction rate,the amplitude limits of 23-order wheel polygon are given at speeds of 200km/h,250km/h and 300km/h.(4)Based on the modified Miner linear cumulative damage theory,the fatigue life prediction of the bogie under wheel polygon excitation was carried out.The fatigue life of the frame is calculated by the combination of multi-body dynamics and finite element simulation.The fatigue life prediction applicable to high speed conditions needs further study. |
