Viscoelastic Properties of Longitudinal Waves in a Hollow Cylinder

The attenuative and dispersive properties of longitudinal waves propagating in a viscoelastic materials over a wide range of frequencies were examined in this work. The first order mode vibrations of the waves propagating in a viscoelastic solid bar were measured, and the material properties were determined in the previous research. The ultrasonic wave propagation experiments by using the ultrasonic transducers having several characteristic frequencies were carried out with the hollow cylinder of a polymethyl methacrylate (PMMA) material. Then, the material properties are identified as a 5-element solid model based on the three dimensional exact theory. As a result, the attenuative and dispersive properties were able to be determined more accurately by taking into account only the first order mode vibration in the low frequency region and both the first and second order mode vibrations in the high frequency region.