SOUND REFLECTION AND TRANSMISSION OF COMPLIANT PLATE-LIKE STRUCTURES BY A PLANE SOUND WAVE EXCITATION

The sound transmission and reflection by an infinite compliant plate-like structure immersed in fluids are analyzed using an exact method. A matrix formulation for the submerged plate with a stack of arbitrary number of anisotropic or isotropic layers, and subject to a plane sound wave excitation, is derived to obtain the transmission and reflection coefficients in the frequency domain. The coupling between the fluid and plate is taken into account in a rigorous manner. Several application examples are used to evaluate the effects of the thickness of the coating layer and base plate, the mutual position of layers, and the damping loss factors on the sound transmission and reflection. Results show that the coating layer attached to a steel base plate can effectively decrease the sound reflection by an average amount of about 6 dB above a frequency of 10 kHz when the coating layer of thickness 100 mm is on the incidence side.