Analysis And Optimization Of Structure Noise Characteristics Of A Passenger Car Body

With the development of the automotive industry and the rapid update of science and technology,NVH performance,which is closely related to human comfort,has gradually become the key indicator for consumers to pay attention to when purchasing vehicles.The lowfrequency noise related to the structure of the vehicle will cause discomfort to the drivers and passengers inside the vehicle,greatly reducing the comfort of the occupants.Therefore,automotive oems and various research institutes will spend a lot of energy and resources to study the acoustic characteristics of low-frequency noise in the vehicle,and the level of NVH performance index has gradually become the key to the market competitiveness of vehicle research and development.Considering the fact that the vibration noise of the driver’s right ear is too large in a certain fuel car at a steady speed of 30km/h,the noise characteristics of the passenger car body structure are analyzed and optimized.The main contents of this topic include:(1)through experimental researches on the paths under the peak frequency,through LMS Test.The Lab software 30 km/h at a constant speed in steady state under the condition of real vehicle Test for driver’s right ear of the sound pressure level spectrum,based on the principle of the OTPA analysis of the sound pressure level spectrum peak frequency analysis of the operation flow path,finally find out the path of the right ear sound pressure greater contribution to the driver.Singular value decomposition(SVD)and principal component analysis(PCA)were used to process the test data,and the spectral maps of the contributions of each transfer path were obtained.(2)To explore and investigate the dynamic characteristics of the body structure and the performance of the whole vehicle,build the finite element model of the car body in white and the whole vehicle based on the finite element theory,and complete the free mode analysis of the body in white based on the structural modal theory,thus having a preliminary understanding of the dynamic characteristics of the white body.At the same time,based on the dynamic stiffness theory,the dynamic stiffness analysis of the white body between the chassis and the attached points of the body was completed.By the stiffness analysis,the performance of the vehicle was understood to some extent.(3)The interior acoustic characteristics of the vehicle were studied systematically,and acoustic cavity modal analysis was completed based on the acousto-solid coupling theory.The results showed that the distribution of sound pressure in the vehicle was basically reasonable.The frequency response of the cavity model was studied in depth,and the response curve of the noise transfer function under road noise excitation was obtained through analysis,and the reliability of the simulation model was verified by comparison with the sound pressure level spectrum curve of the driver’s right ear obtained under test.(4)A scheme of vehicle noise optimization based on multi-objective topology optimization theory is proposed.Based on the theory of acoustic radiation of thin plates and the contribution of sound pressure,the contribution of plate components was analyzed,and the frequency distribution characteristics of the contribution of each plate to the interior noise under the peak frequency were analyzed to determine the plate with a large contribution to the sound pressure at the response point.Based on the multi-objective topology optimization,the structural optimization of the plate which contributes a lot to the sound pressure at the response point is completed.Finally,the simulation results show that the interior noise is effectively improved.