On acoustic performance for viscoelastic coating containing axisymmetric cavities using the multiple scattering method

A semi-analytical/numerical model based on the multiple scattering(MS) method has been established for analyzing the effect of acoustic performance on main energy attenuation mechanism in viscoelastic coating containing axisymmetric cavities.The basic functions of stress and displacement of the axisymmetric cavity surface are derived in the system of spherical coordinates.The transition matrix between the incident wave and the scattering wave are obtained by the numerical integral of the basic functions of the cavity surface.The reflection,transmission and absorption performance of viscoelastic materials containing periodic cavities are calculated using the MS method and the wave propagating theory of the multi-layered medium.The results indicate that low frequency energy is mainly attenuated through cavity resonance.The resonant properties are found to be very sensitive to the boundary conditions.The coupling of the double-cavity is capable of extending the absorption to even lower frequencies.The absorption performance of the viscoelastic coating in the high frequency range is independent of the backing material.Its energy attenuation depends mainly on acoustic properties of cavity scattering and mode conversion.