Attenuation and Dispersion Characteristics of Various Plastics in the Frequency Range 1-10 MHz

It is observed experimentally that PMMA, phenolic and various polyester resins exhibit little dispersion but significant frequency-dependent attenuation for dilatational waves in the frequency range 1-10 MHz. It is also shown that the shape of a low amplitude stress pulse propagating through a material with the above characteristics becomes significantly altered after propagating only a few cm. Thus the stress pulse distortion observed in plastic matrix-type composite materials may not be attributed to geometrical dispersion and attenuation alone; material attenuation in the matrix must be considered. The representation of these plastics by a standard linear viscoelastic solid is shown to provide an adequate model of the experimental data for the stated frequency range.