Statistical Energy Analysis On Interior Noise Control Of Passenger Car

Automobile is the powerful transportation that drives the industry, agriculture, communication and tourist industry. With the rapid increase of the automobiles, vehicles become the main source of the urban noise pollution. The automobile is a part of modern life, and the interior noise worsens the environment of drivers and passengers to some extent. How to enhance the acoustic performance of vehicles and reduce the vibration means a lot to the comfortableness of vehicles.The competition becomes more and more drastic, it is necessary for the designers to take the acoustic behavior of automobiles into the consideration in an early stage of development. The Statistical Energy Analysis is suitable for prediction tasks. SEA is an effective way to forecast the response of vibration and noise. As to the existing cars, it is easy to predict the acoustic optimization effectiveness of all kinds of optimized treatments to the car by SEA. SEA method is used to develop the new technology and new materials for acoustic optimization. The simulation and prediction by SEA can reduce the cost and shorten development cycle.On the basis of references about interior noise and SEA, the simulation and analysis about the existing car was carried on in this paper. The author did some research on SEA full vehicle model.At first, the 3D car was modeled in 3D software. Secondly, the model is imported into the AutoSEA2 for further work. Divided the full car system into several subsystems according to the rules about the SEA subsystems. Defined the physical properties of subsystems in the database of the software.The basic parameters of SEA: model density, damping loss factor (DLF) and coupling loss factor (CLF) were obtained by theoretical computation and test. The DLF of panels were obtained by theoretical computation. The DLF of interior cavity was obtained through the test and data process, the reverberation time test was carried on in anechoic room. The model density and CLF were computed bysoftware.The excitation of full car system is obtained by experimental methods and simulation. Measured the engine suspension point force, sound pressure of engine room and sound pressure of back side of rearview mirror. They acted as the input excitation of vehicle system. The excitation of road through suspension was obtained by simulation in ADAMS. Data process was carried in MATLAB. At the same time, the sound pressure of driver's head area was used to be compared with the simulation results.Imported the excitation data to AutoSEA2, applied them to the full car system for further computation. After the computation, compared the simulation results with the test results, analyzed the reasons of error in mid and lower frequency band, the two curves agree with each other in higher frequency band, and the error meet the computation requirements. So, the results illustrated the feasibility of SEA in acoustic simulation.The paper took the trimmed body into consideration. Through the analysis of plate contribution curves and cavity input power curves, the paper brought out some optimized treatments, and simulated the optimized results. The acoustic material can optimize the inner cavity of vehicle, and increase the DLF of interior cavity, so the interior noise of vehicle can be reduced effectively because of the acoustic materials, especially in high frequency band. The damping material can reduce the vibration of vehicle body, the DLF of floor, firewall and fender were increased, and so the radiation energy of body was reduced, the interior cavity sound pressure level decreased. The results show that the damping material of fender and floor means a little to the interior noise, because they lies mainly far from the sound source. Thickened the firewall, the surface density was increased, so the radiation power from engine room decreased, and the radiation energy to interior cavity decreased. The combination of acoustic material and damping material can reduce the interior noise effectively, especially for high frequency band noise. The thicker side glass can optimize the interior acoustic behavior.