Mechanism Analysis of Sound Absorptionof Alberich Coating at Low-frequency
Tao Meng1; Tang Weilin2
1. State Key Laboratory of Mechanical System and Vibration,Shanghai Jiao Tong University, Shanghai 200240)(2. School of Naval Architecture; Ocean and Civil Engineering,Shanghai Jiao Tong University, Shanghai 200240
Abstract： The axisymmetric wave propagating along the thickness direction of Alberich sound absorption coating is excited in the case of normal incidence, and the axisymmetric wave with the lowest order which determines the low-frequency performance of sound absorption can be approximated as a quasi plane wave. The mechanism of sound absorption of Alberich coating is analyzed by using the resonance theory, and the relationship between the phase velocity of axisymmetric wave and the lowest peak frequency of absorption coefficient is obtained. The mechanisms of sound absorption at low-frequency include that: (1) the coating resonance is referred to the resonance of viscoelastic cylindrical tube; (2) the peak frequency of absorption coefficient is corresponding to the anti-resonant frequency, rather than resonant frequency of coating; (3) the lowest peak frequency of absorption coefficient in the case of soft backing is half of that in the case of rigid backing.
2011, Vol. 30 
