| With the continuous improvement of the running speed of high-speed train,the incentive energy of the train in operation state increases accordingly.At the same time,the vehicle conditions are also very complex.In the process of running,the vibration of body structure has obvious randomness,which will greatly change the performance of the vehicle.When the train is subjected to random load for a long time,its structure will appear fatigue damage,which will affect the service life of the train body.Therefore,with the development of high-speed train in the direction of high speed and light weight,it is of great significance to study the vibration performance of car body structure,which plays a key role in improving the safety and stability of high-speed train operation.In this paper,a high-speed train body is taken as the research object,and based on the basic principle of random vibration,the fatigue life of high-speed train body is predicted by using the simulation analysis method combining finite element method and dynamic theory.The main research contents of this paper include the following aspects:(1)Establish the finite element model of the body of a high-speed train,conduct modal analysis and static strength analysis of the body according to the standard EN12663-2010,and determine the natural frequency and weak parts of the body.The results show that the maximum stress of the car body is 193.6MPa,which is less than the allowable stress of the aluminum alloy used for the car body and meets the standard requirements.The first order vertical bending mode frequency of the car body structure is 13.33 Hz,which is greater than the 10 Hz stipulated in the standard,and the car body mode meets the standard requirements.(2)Establish a multi-body dynamic model of a single carriage of the high-speed train.The time-load history of the air spring position in the transverse,longitudinal and vertical directions of the vehicle dynamics model was extracted and converted into the power spectral density in the frequency domain,which was used as a random excitation to predict the fatigue life of the vehicle body.(3)The frequency response of vehicle body vibration is analyzed by grouping calculation method.Rigid elements are used instead of train air springs to simulate the connection between the body and bogie.The frequency response of the car body was analyzed by applying lateral,vertical and vertical acceleration loads to the air spring of the car body,and the frequency response function of the car body was obtained.Group calculation method is used to calculate the dynamic response at key positions under random loads.(4)The vehicle body life of high-speed train is calculated with different running speeds and frequency domain calculation methods as variables.The comparison results show that when the train speed is the same,the results of the Dirlik method in the frequency domain calculation method are conservative,and meet the requirements of the four-level maintenance standard of the train.When the calculation method is the same,trains running at different speeds have different service life.With the increase of running speed,the vibration fatigue life of train decreases gradually.When the train runs at 380km/h,its operating mileage life is4.67 million kilometers,meeting the maintenance standard of 2.4 million kilometers.This paper takes the high-speed train body as the research object,establishes the dynamic model of the body,takes the track spectrum excitation as the random load,and proposes the method of group calculation to calculate the dynamic response of the body at the key position.Combined with S-N curve of car body material and fatigue damage accumulation theory,the fatigue damage and life of car body were analyzed.Compared with small component structures,this paper uses computer virtual simulation technology to save the labor and time cost of real vehicle test,and provides an analysis method for simulation calculation of vibration fatigue life of high-speed train body,a large complex engineering structure. |
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