SEDL / STP / STP1059-EB / STP24124S

Analytical and Experimental Investigations of Composites Using Vibrothermography

Lin, SS
Graduate research assistant and professor, Material Response GroupVirginia Polytechnic Institute and State University, Blacksburg, VA

Henneke, EG
Graduate research assistant and professor, Material Response GroupVirginia Polytechnic Institute and State University, Blacksburg, VA

Pages: 18    Published: Jan 1990

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Abstract

Vibrothermography uses real-time video thermography for nondestructive evaluation of a structure or component excited with mechanical vibration. During vibrothermo-graphic testing of composite materials, it has been found that conditions for the generation of a thermal pattern are strongly dependent on the frequency of excitation. A local resonance model was proposed to describe this behavior, and several experiments were performed to verify this model and to qualify the heat generation mechanism. A significant conclusion of the results is that the local resonance model is indeed the mechanics model for the frequency-dependent heat generation behavior. The experimental results also show that the majority of heat generation during vibrothermographic testing results from higher stresses and strains due to local resonance. The heat generation was affected by the combination of the principal strains and shear strain for the lower modes of resonant vibration, and it was dominated by the shear strain for the higher modes of resonant vibration.