Structural Strength And Fatigue Analysis Of Intercity Train Gearbox

With the continuous development of urbanization in China,intercity trains have been applied more and more widely.In recent years,due to the continuous improvement of train speed,the dynamic load borne by train transmission system is more complex than before.As one of the key components of intercity train transmission system,the strength and fatigue of gearbox under the impact and random vibration load of the line have been paid much attention.Firstly,this paper summarizes the correlation analysis of the gearbox body at home and abroad.Then the impact strength and random fatigue of the gearbox were studied based on the relevant standards.The rigid-flexible coupling dynamics simulation model was established,and short-wave track irregularities were introduced to obtain the vibration fatigue life of the gearbox body under high frequency excitation.The specific research contents are as follows:(1)Firstly,solid elements are used to discretely process the geometric model of the gearbox,and the finite element model of the gearbox body is established.Lock Lanczos method was used to calculate some low-order modes of the gearbox,and the validity of the gearbox body model was verified by comparing the calculated modes with the modal results obtained by hammer test method.(2)In order to analyze the impact resistance of the gearbox structure,the impact load in IEC 61373-2010 Locomotive and Rolling Stock Impact and Vibration Test Standard is taken as the input condition,and the quasi-static method and the transient dynamic method are respectively used to calculate and evaluate the impact strength of the gearbox body.The results of the two methods show that the maximum stress of the gearbox is less than the yield stress of the material of the gearbox and the gearbox meets the strength requirements.(3)Based on the simulated long-life random vibration load in IEC 61373-2010 standard,the random vibration analysis of the gearbox body structure is carried out.First calculate the longitudinal,transverse and vertical three directions of the maximum principal stress transfer function,obtain stress power spectral response were calculated based on random vibration theory,in order to prevent the effects of phase Angle,introduced Fourier inverse transformation,this paper,by using stress power spectral statistical method of Dirlik stress change range and cycles,The fatigue life of the gearbox is analyzed by random vibration.(4)In order to obtain the vibration fatigue life of the gearbox structure under the condition of track operation,the rigid-flexible coupling dynamics simulation method was adopted in this paper to conduct vibration fatigue analysis.The flexible body of the gearbox was formed by the improved Craig-Bampton modal synthesis method,and the rigid-flexible coupling vehicle dynamics model was established.Meanwhile,the contribution of high frequency track excitation to the vibration fatigue of the gearbox was investigated.The short-wave irregularities were added into the track irregularities,and the line operation was simulated with the track irregularities as the excitation.The fatigue life of the improved structure is compared with that of the original structure,and the results show that the fatigue life of the improved structure is greatly improved compared with that of the original structure,which meets the design service life requirement of 12 million km.