| The noncircular rail wheel with polygon shape caused by abnormal wheel wear may be in all probability rose with the operating mileage and continuous increase of train speed,the noncircular rail wheel produced by wheel tread polygon wear have become one of the main causes of vehicle interior noise.In this paper,the characteristics of train interior noise and wheel polygon are researched by means of experimental test and numerical simulation.The main contents are as follows:(1)Interior noise data has been obtained by the tracking test of interior noise on three models EMU named A,B,C,and the spectrum characteristics of all the noise data have been obtained by the spectrum analysis;(2)A database management system based on SQL Server has been established by using Visual Studio 2010(C#)to store and manage the test data and the results of spectrum analysis;(3)The distribution laws of interior noise have been analyzed from the aspect of the total sound pressure level and frequency respectively,which mainly include the relationship between the head coach and the intermediate coach,the different models of EMU,the operating mileage and interior noise,found that the frequency of 580 Hz noise is the main part of the interior noise,and it is verified that the 20 th order polygon feature is the main cause of the large interior noise by comparing with the high order excitation frequency of the wheel;(4)Interior noises before and after wheel turning repair have been tested respectively,the results show that the noise level is obviously reduced after wheel turning repair,and the wheel turning repair can alleviate the high order polygon state and decrease wheel diameter jump amplitude effectively;(5)A wheelset of trailer bogie for A type EMU has been taken as a research object,its finite element model and the infinite element model have been set up in order to calculate the vibration and noise,the vibration responses and acoustic power spectrums of wheelset have been achieved,and the acoustic radiation characteristics at the peak frequency have been analyzed by a direct frequency response analysis;(6)A modal analysis of wheelset structure has been performed,it is found that there is a one-to-one correspondence between the peak frequency of the acoustic radiation and the natural frequency of the structure,and the displacement response at the peak frequency is basically the same as the modal shape of the same frequency,it is pointed out that the structural resonance is the main cause of noise radiation increase;(7)The excitation frequencies of the wheel polygon have been calculated,it is predicted that the 20 th order wheel polygon was caused by the 3rd order bending vibration of wheelset by analyzing the mechanism of wheel polygon wear;(8)Taking A type EMU body as the research object,a coupling vibration model of EMU body and interior sound field has been established based on the FE / IE method,the frequency responses of the interior and exterior acoustic field have been calculated at the same time by taking the displacement response of wheelset as excitation,and the interior noise characteristics have been analyzed,found that the distribution of sound radiation is consistent with wheelset;(9)The acoustic modal analysis of the inner cavity has been carried out,the results show that there is a multi-order acoustic mode near the frequency of larger noise value,therefore the acoustic resonance of the carbody inner cavity would also effect the interior noise level. |
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