The Operating Modal Analysis Of Gearbox In High-speed EMU

In recent years,with the development of high-speed rail lines,the sacle of high-speed train's use has gradually expanded.And since some high-speed trains were operated in the Beijing-Shanghai and Wuhan-Guangzhou line,various box crack failures have occurred in gearbox which have a great impact on production and operation.Therefore,it is very important to study the vibration problem of gearbox housing.As a result,it is necessary to analyze the vibration characteristics of gearbox housing under actual operating conditions.In this paper,the modal test and research on vibration characteristics of assembled gearbox housing of a domestic type of EMU were carried out.According to the physical structure of gearbox and its related parameters,the finite element calculation of the free mode and the restraint mode of the gearbox was carried out,and the arrangement of measuring points in modal test was determined.Based on the actual assembly constraints of the box,the design,assembly and commissioning of the vibration test table were completed,and the beam pre-test was conducted to develop the functions of the test.In addition,the results showed that the natural frequency of the test equipment is much smaller than that of the gearbox housing,and the rationality of the equipment's design was verified.The multi-band random excitations were taken to excite the gearbox housing and the methods of PolyMAX and continuous wavelet transform combined with singular value decomposition were used to identify the parameters of the first six order modes of gearbox housing.The advantages and disadvantages of the two methods were compared as well.For the false modals that appeared in the parameter identification process,the main vibration source which came from the axle and the axle box was determined with the hammering method.The influence of modal parameters and other frequency components on the vibration of the gearbox housing under the disturbance of the line was investigated,and the main vibration forms of the gearbox housing were determined under the line condition.The vibration transmission in the vibration path of the vibration table,shaft and gearbox was studied by time domain method,frequency domain method and acceleration spectrum method.The results showed that for the lateral excitation between wheel and rail,the gearbox housing was prone to resonance,and the vibration was more intense,but for the vertical excitation between wheel and rail,the attenuation effect of gearbox was obvious.The above research process has completed the research of modal parameter's identification and vibration transmission of gearbox in assembly state,and also provided the method and basis for finding the cause of box crack under line disturbance.