| The regional Electric Multiple Units have developed rapidly in our country with the advantages of fast,comfort,energy saving and environmental protection.The increase of the speed of the coach must cause serious interior noise,especially the noise of the rear end of the coach.Aimed at the interior noise problem of 250 km/h EMUs,the characteristics and contributions of interior noise sources are analyzed by means of test and simulation.Firstly,based on the field measurement,the distribution,frequency and intensity of the sources are obtained.Then the main sources are identified in the areas of door by the spherical acoustic array and the area contribution is analyzed.Secondly,the modal density,damping loss factor,coupling loss factor and transmission loss of car body structures,such as floor,sidewall,roof and headwall,are obtained from the laboratory test results.The sources from the field measurement result and the parameters of plate structures of the model from the laboratory test results are applied into the SEA modal.Then the prediction results are compared with the test results and the model is verified.Finally,based on the interior noise prediction modal,the response of sound pressure is calculated and the spatial distribution of noise is identified.Then the contribution of power input is analyzed to find the main sources and noise transmission paths and analyze the contribution of noise sources.The results show that the interior noise sources are mainly form the bogie area noise and the contribution rate is above 30%.The body surface area noise is secondly noise source and its contribution rate is above 20%.The vibration of the sidewall is also the key factor and its contribution rate is 15%.And the influence of the interior noise is investigated from the control of noise sources and paths,which provide reference for interior noise control for regional EMUs. |
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