Research On Acoustic Materials Applied In Auto Noise Reduction

As technology develops rapidly today, the society continues to progress, people’s living standards have improved steadily. When consumers buy cars, they not only focus on vehicle dynamics and economy, but also pay attention to riding comfort. Vehicle noise, as one of the important indicators of riding comfort, gets more and more attention. In order to achieve the purpose of reducing noise, researchers and engineers have done a lot of research work in vehicle noise control, and achieved remarkable results. The paper is based on the finite element method(FEM), and uses ACTRAN software. Trim model, which is composed of acoustic material, is applied to coupling system, which is composed of car body model and passenger compartment model. The paper studies on noise reduction effect of acoustic materials, and studies on noise reduction effect of the acoustic materials’ properties in depth.Firstly, the main acoustic materials used in the paper are viscoelastic damping material and porous sound-absorbing material. Based on the theoretical model of them, the basic model of the acoustic material is established. Based on the transfer function method, experimental reseaech is carried on the absorption coefficient of the porous sound-absorbing materials, the absorption coefficient directly reflects the noise reduction effect of the material, and sound-absorbing materials can be chosen the initial by this method preliminarily.Secondly, based on the modal theory, the paper conducts modal analysis on automotive body and acoustic space of passenger compartment, which reflects the inherent characteristics of the automotive body and noise characteristics. Then the coupling analysis of the body and the passenger compartment is conducted. By changing the magnitude of the excitation, the sound pressure level of the driver’s right ear in the analysis results is adjusted to about 75 d B. Based on this, the acoustic material added to the coupling system on the location of roof and floor location, then the coupling analysis is conducted based on reduced impedance matrix method. The results show that, after adding acoustic materials, the sound pressure level of the driver’s right ear declines dramatically, and the declined amplitude is about 13 d B.Finally, the paper studies the effect of noise reduction effect of diverse properties of damping material and porous sound-absorbing material. Considering the coupling model in which the acoustic material was added, as a standard model, and changing the relevant properties of acoustic material, analysis is carried on new model. The main analysis is on the separate noise reduction effect of the roof and floor acoustic material, on the noise reduction effect of thickness, the flow resistance and porosity of the porous sound-absorbing material, young’s modulus and viscoelastic damping of damping material. Through research, we can get the noise reduction law of acoustic materials’ related properties, which has applied value and reference meaning to car noise control.