Research On Fatigue Reliability Of CR300BF EMU Gearbox Housing Based On Tracking Test

As the key transmission component of high-speed EMU,gearbox bears complex alternating load in practical application,and its safety and reliability is an important link to ensure the normal and safe operation of the transmission system and EMU.In the course of long-term service in bad conditions,the strength of gearbox structure is constantly challenged.When the damage accumulation of gearbox exceeds the critical value,fatigue cracks and other failure forms will occur,leading to fatigue damage,seriously affecting the safe operation of the train.Therefore,it is necessary to study the fatigue reliability of the gearbox of Chinese standard EMU.In this paper,the gearbox developed by three different manufacturers of cr300 bf standard EMU is taken as the research object,and the fatigue reliability of the gearbox is studied through the long-term tracking test of the dynamic stress and acceleration measured data in the test of Chengdu Guiyang passenger dedicated line,combined with the finite element analysis and other research methods.The main contents are as follows:(1)According to the standard and the technical parameters provided by the manufacturer,the finite element analysis software is used to model and calculate the structural strength.The fatigue reliability of the gearbox is analyzed and studied.The stress distribution results of the gearbox under the operation load and the abnormal load are obtained,which provides the basis for the selection of the test points of the line test.(2)Based on the measured data of dynamic stress,the time-domain and frequency-domain characteristics of dynamic stress at each measuring point under typical working conditions are analyzed.The vibration energy frequency range of each gearbox is analyzed under the condition of constant speed,and the vibration source is studied.Under the condition of acceleration and deceleration,the dynamic stress time-domain and frequency-domain vibration characteristics of each gearbox are studied.In the up-run and down-run,the vibration energy distribution characteristics of each measuring point in the up-run and down-run of the gearbox and the effect force comparison of three kinds of gearbox up-run conditions are studied.(3)Based on the measured acceleration data,the time-domain and frequency-domain characteristics of acceleration at each measuring point are analyzed.From the time-domain analysis,under the same working condition,the acceleration of each measuring point of the gearbox is compared with that of each other,and the effectof vertical lateral vibration of each measuring point of three kinds of gearbox on the excitation of the gearbox is analyzed.From the frequency domain analysis,the relationship between the energy value of the main frequency band of the gearbox vibration and the train speed and the distribution characteristics of the main frequency of the vibration in the acceleration and deceleration stages are analyzed.In the stage of constant speed,the main frequency characteristics of three kinds of gearbox test three-way acceleration vibration are studied,and the resonance phenomenon is explored.(4)Based on the measured data of the whole dynamic stress,the life prediction of the gear box is carried out.According to the S-N curve and miner's rule,the measured stress spectrum of the whole line is compiled,the measured damages of the gearbox are calculated and the life prediction is made.