Vibration Fatigue Performance Analysis Of High-speed Train Body Structure Based On Track Spectrum

The speeding up of the high-speed train on the track will lead to the increase of the load frequency and load energy of the railway vehicle.At the same time,the running condition of the vehicle body is complicated,and the vibration type of the vehicle body structure in operation is random,which will have a great impact on the vehicle structure.Fatigue damage will occur to the railway vehicle structure due to the external excitation of the track irregularity for a long time.Therefore,the study on the vibration performance of the car body is of great significance to the safety and stability of high-speed trains.Therefore,based on the theoretical basis of random vibration and the external excitation of track spectrum,this paper uses the simulation method combining finite element and dynamics to analyze the vibration fatigue of a certain high-speed train body structure and predict the life mileage of the car body.The main research contents are as follows:(1)Collect the time-domain signals at the air spring of the vehicle body based on different track spectra,and convert the time-domain signals to frequency-domain signals through Fourier transform.In Simpack software,the multi-body dynamics model of a single car body is established.Dynamic simulation of high-speed trains at different running speeds is carried out by using Chinese high-speed track spectrum and German low disturbance track spectrum as track excitation.The longitudinal,transverse and vertical acceleration responses at the air spring of the car body are obtained,and then the random acceleration in the three directions is transformed into the acceleration power spectral density by Fourier transform.The conversion results show that the power spectral density is mainly concentrated in the low frequency range of 3-15Hz.(2)The finite element model of a high-speed train body was established,and the static strength analysis of the car body was conducted according to the design standard EN12663-2010.In the form of mass concentration point,it is applied to the corresponding position of the vehicle body to simulate the vehicle body preparation state,and the modal analysis of the vehicle body structure is carried out.The results show that when the vehicle structure mode is in the first order vertical bending,the corresponding frequency is 11.56Hz,greater than the national standard of 10Hz,in line with the vehicle body modal requirements.(3)Frequency response analysis of the car body.The air spring of the car body structure is connected by a rigid unit to simulate the connection between the car body and the bogie.The unit acceleration of 9800mm/s~2 is applied to the connecting position of the car body respectively in the longitudinal,lateral and vertical directions,and the direct method frequency response analysis of the car body is done.(4)With the track spectrum,frequency domain statistical method and running speed as different variables,the fatigue damage calculation and life range prediction are carried out in the key position of the vehicle body in Ncode software.Compared with the train running at 350km/h,the fatigue damage of the critical position of the train structure caused by the high-speed rail spectrum in China and the low interference rail spectrum in Germany were compared;Taking the low disturbance track spectrum of Germany as an example,the fatigue damage of the critical position of the train structure under different frequency domain statistical methods is compared when the train is running at an speed of 300km/h;Under the excitation of the same track spectrum,the fatigue damage of the critical position of the train body structure at different speeds is analyzed.According to the above fatigue damage data,the life range of vehicle body is predicted.The results show that the life range of the car body meets the design requirements of the car body.This paper provides an analytical method for the vibration fatigue life calculation of high-speed trains.