WAVE PROPAGATION IN MEDIA OBEYING A THERMOVISCOANELASTIC MODEL

The aim of this work is to investigate mechanical phenomenological and state coefficients taking in account irreversible processes in isotropic viscoanelastic media of order one. In the contest of Kluitenberg-Ciancio theory we consider the case of linear transverse acoustic wave of high frequency propagates in such a medium showing that the aforementioned coefficients assume a particular form as function of complex wave number. By mean of considerations on linear phenomenological acoustic theory, we determine a connection between complex wave number and shear complex modulus, and so we are able to express phenomenological and state coefficients as function of complex shear modulus. The experimental knowledge of such a modulus, as function of the frequency, allow us to experimental evaluation of the aforementioned coefficients. This approach has been applied to polymeric materials as PolyIsobutilene.