Research on sound absorption characteristics of Alberich anechoic coatings in debonding states

Viscoelastic structures with periodic cavity arrangement occupy an important position in acoustic stealth. Most studies focus on the absorption at low frequency, under large pressure and in a wide frequency band, however, the sound absorption properties of the anechoic coating in debonding states are seldom studied. The acoustic response of the composite structure is calculated by the FEM, and the incident wave and the reflected wave are separated based on the plane wave propagation principle. The sound absorption coefficient of the model can be solved with the pressure data of transmission wave, incident wave and reflected wave. Based on the finite element method, the absorption characteristics of anechoic coating in debonding states have been studied. Firstly, the FEM model is verified by comparing the solution of uniform non-cavity coatings with the corresponding analytical solution. The results indicate that the problem of acoustic pressure field can be simulated well by the symmetry condition and the absorbing boundary. Then, the Alberich anechoic coating models in different debonding ratio states and in different cavity water filling states are established by FEM, and then the corresponding absorption characteristics are calculated and analyzed. The results show that the effects of debonding on absorption characteristics are small when the cavities of coatings are filled with water, however the effects are much more when the cavities of coatings are filled with air. For the case of cavities filled with air, the main frequency band of sound absorption moves to low frequency with the debonding ratio increasing. When the frequency is very high, there are few impacts on the sound absorption coefficient no matter whether the packing medium is water or air, no matter whether the coating is debonding or not