Research On Modeling Method Of Subway Train Noise Prediction With Running Conditions On The Ground

With the gradual improvement of China’s urbanization level,people’s demand for urban travel is also gradually increasing.The continuous improvement and development of subway construction has brought great convenience to people’s travel.However,the running of subway trains has also caused very serious noise pollution.This paper mainly proposes a modeling method for predicting subway train noise with running conditions on the ground,and verifies its effectiveness by comparing the experimental and simulation values,the purpose is to provide guidance for noise control of subway trains.The specific research contents are as follows:Firstly,based on the principle of measuring structural damping by free decrement method,the damping ratio test of profile samples of subway train floor,side wall and roof were completed.A new calculation idea is proposed,to avoid the problem that when the damping ratio is directly calculated in the 1/3 octave frequency band,it is necessary to identify multiple sections of different attenuation curves caused by multiple modes in the frequency band.And using MATLAB programming to process the experimental data,ang get the damping ratio data of various profile samples.Next,based on the principle of sound insulation testing in the laboratory,the sound insulation test and simulation calculation of floor,side wall and roof profile samples were completed.By comparing the calculated sound insulation data with the experimental value,the validity and accuracy of the simulation calculation are verified.Then,the sound insulation simulation models of the side walls and the floor components were established,and their sound insulation was calculated to provide data support for the simulation calculation of subway train noise.Finally,a modeling method used to predict the subway trains noise with running conditions on the ground was proposed,and the model was established by using VA one software based on Statistical Energy Analysis theory.By comparing the simulated value of the interior and exterior noise with the measured data,it is found that the simulated interior noise value is on the high side.By analyzing the power inflow contribution rate of the interior acoustic cavity,it is found that the reason for the oversized interior noise simulation value is that excessive noise energy of the bogie area is laterally transferred to interior acoustic cavity through the exterior annular acoustic cavity.Therefore,the model was improved by dividing the original annular acoustic cavity,to reduce the sound energy transmitted to the interior cavity through the exterior annular acoustic cavity.By comparing the simulation data with the measured noise value again,and analyzing the power inflow contribution rate of interior acoustic cavity-"1.6-middle",it is verified that the improved model can accurately predict the noise inside and outside the subway train.