- Conference date: 26–31 July 2009
- Location: Kingston (Rhode Island)
An ultrasonic measurement method has been developed for use in characterizing the thin surface layer of property changes that develops for polymeric materials exposed to long term high temperature environments. The method involves creating a Rayleigh surface wave with a wavelength similar in size to the depth of the degraded layer (∼200 microns). Since typical wedge transducers are incapable of generating Rayleigh waves in most polymers, a mediator wedge transducer method has been designed to effectively serve as a line source for the ultrasonic wave. High resolution noncontact signal detection is accomplished through the use of a laser vibrometer in order to adequately provide data for automated calculations of velocity and attenuation. The successive events of wave generation, detection, and analog signal processing have been simulated for measurements on an epoxy specimen with an explicit finite element method and representative mathematical post processing algorithms in order to better understand the measurements and their application usefulness. A comparison of the preliminary simulation data and the experimental measurements provides useful insights about the data patterns detected in the experiments.
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