Transmission and Reflection Characteristics of Viscoelastic Plates,

摘要

An acoustic transmission matrix program for computing transmission (S) and reflection (R) coefficients for sound waves of arbitrary frequency, incident at arbitrary angles upon viscoelastic plates bounded by semi-infinite fluids, has been developed. The method, an extension of the formulation of Young for elastic plates, utilizes the elastic and viscoelastic material properties of plates and the program is applied here to the problem of choosing materials for acoustic windows and acoustic lenses. The materials considered are Absonic-A, polyethylene and syntactic foam. Computed results are given in the form of transmission and reflection loss and presented as functions of incidence angle and frequency, and are interpreted in terms of the propagation and material constants and modal and half wave plate resonances.