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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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For many years, electroactive polymers (EAP) received relatively little attention due to the small number of available materials and their limited actuation capability.
Reported on is the development of a quantitative NDE method, using stiffness analysis, for the determination of the degradation of composite materials that are exposed to elevated temperatures, prior to the formation of delaminations or other defects. Methods of testing describe a specimen immersed in water and subjected to ultra- sound, with reflected pulses or tone-burst (leaky Lamb wave) analysis.
From Intro: In this paper, wer apply the LLW (leaky Lamb Wave) technique to determine the stiffness constants of unnidirectional graphite/epoxy materials...In this paper, we describe a new technique which can be used to determine all five stiffness constants by analyzing the times-of-flight of the recorded reflected acoustic waves in a pulsed LLW experiment.