Theoretical Calculation and Analysis of Muffler Based on Multilayer Sound Absorbing Material

The multilayer impedance composite sound absorption structure of the new muffler is proposed by combining the microporous plate structure with the resonant sound absorption structure of the porous material. Firstly, the acoustic impedance and acoustic absorption coefficient of the new muffler structure are calculated by acoustic electric analogy method, and then the noise attenuation is calculated.When the new muffler structure parameters change, the relationship among the noise frequency, the sound absorption coefficient and the noise attenuation is calculated by using MATLAB. Finally, the calculated results are compared with the experimental data to verify the correctness of the theoretical calculation. The variation of resonance peak, resonance frequency and attenuation band width of each structural parameter is analyzed by the relation curve. The conclusion shows that it is feasible to use multilayer sound absorbing materials as the body structure of the new muffler. And the influence relationship between the change of various parameters of the sound absorption structure with the sound absorption coefficient and noise attenuation is obtained.