A New and Simple Method of Solid Polymeric Acoustic Characterisation by Means of the Electrical Impedance Modulus

We purpose, in this paper, a simple and original method to determine the velocity and absorption coefficient of compressional acoustic waves propagated in isotropic solid materials. It is based on electric impedance measurements in a frequency bandwidth around the transducer resonance frequency. The impedance measurements, in the same frequency bandwidth, of a transducer unloaded and loaded by the sample permit the determination of electric impedance of acoustic line, constituted by the load. Its modulus processing gives the material acoustic properties. We first develop a theoretical part to determine the absorption coefficient and velocity expressions from the impedance modulus extremes. Then, we apply this method to characterize some materials (PMMA, Polysulfone, PVC, and Ertacetal). We can also determine the transducer electromechanical transformer ratio.