Bulk shear wave propagation in an epoxy: attenuation and phase velocity over five decades of frequency.
Proportionality between the ultrasonic wave attenuation coefficient in epoxies and other polymers and frequency is a commonly observed but little understood phenomenon. How it is ultimately explained will depend on the breadth of the frequency range over which it is significant. This paper presents results of experiments to measure loss in a single epoxy material over 5 decades of frequency using 4 complementary techniques--dynamic mechanical analysis, microwave excited low-frequency resonances, a novel guidedwave technique based on a metal-epoxy-metal sandwich, and a conventional pulse mode ultrasonic spectrometer. The results are confined to bulk shear waves in the epoxy. They confirm the linear relationship between attenuation and frequency, and it is shown that the broadband behavior of the attenuation and shear wave phase velocity is consistent with the Kramers- Kronig relationships.
Wang
Yujie
Y
Department of Electrical and Electronic Engineering, Applied Ultrasonics Laboratory, University of Nottingham, Nottingham, UK.
Challis
Richard E
RE
Phang
Albert P-Y
AP
Unwin
Marion E
ME
D003198:Computer Simulation; D004852:Epoxy Compounds / Q000737:chemistry*; D008956:Models, Chemical; D012542:Scattering, Radiation; D014465:Ultrasonics
D004852:Epoxy Compounds