Research On Simulation And Analysis Method Of Intermediate And Low Frequency Noise In Vehicle Based On Power Flow

With the continuous development and progress of China's railway network and high-speed trains,railways have become the preferred way for people to travel,and also the key area of China's development In the pursuit of high-speed train speed and lightweight today,the requirement for the level of interior noise is getting higher and higher,which makes the control of interior noise level more difficult.At present,the interior noise level of 400 vehicles operated under 350 km/h can basically meet the requirements of the national standard,but at higher speed,the interior noise level will exceed the limit requirements.Therefore,in order to reduce product development time and improve product design efficiency,it is very economic and key to improve the acoustic performance of the existing vehicle body by means of simulation modeling and analysis,so as to make it adapt to higher speed operating conditions.Based on the theory of statistical energy analysis,this thesis establishes the sound insulation model and fine model of the high-speed train head vehicle,completes the redistribution of each sound insulation index of the head vehicle,makes it meet the requirement of the noise level in the vehicle at 400 km/h speed,and uses the fine model to predict the noise in the vehicle at 400 km/h speed.Firstly,the sound insulation characteristics of the main areas such as the roof,side wall and floor of the vehicle body are obtained by testing the sound energy loss time in the vehicle interior space,and the sound loss factor of the vehicle interior space is obtained.The data of 300 km/h,330 km/h,350 km/h and 370 km/h out-of-vehicle excitation sources obtained from actual line tests are analyzed,and the out-of-vehicle excitation sources under 400 km/h are derived by polynomial fitting.Secondly,the three-dimensional and finite element model of the head vehicle is established according to the drawings.The sound insulation model and the fine prediction model of the head vehicle are established by using the VA-one simulation software.Based on the measured data at 350 km/h speed,the accuracy of the model is verified.At the same time,the energy finite element analysis(EFEA)is applied to the interior noise simulation of high-speed trains and compared with the statistical energy analysis(SEA)method.The results show that the simulation effect of EFEA in 100Hz-250Hz,400Hz and 800Hz band is better than that of SEA.Then,according to the principle of sound isoradiation,the sound insulation of the vehicle body is redistributed.According to the relationship between the power flow of the sound chamber flowing into the driver's cab,sightseeing area and common passenger room area,the sound insulation of the area with poor distribution of sound insulation is partially corrected.After standardization,the sound insulation index of the vehicle body meeting the noise requirement of 400 km/h alighting is obtained.The normalized sound insulation index is applied to the fine model of the headstock to predict the interior noise characteristics at 400 km/h speed.