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On Quantitative Coda Wave NDE for Carbon-Fiber Reinforced Polymers



Ultrasonic coda waves have been applied to concrete and metallic specimens to assess damage with some success. The capability of coda wave NDE for damage diagnosis in fibrous composite materials has not been widely addressed. One method of interpreting the changes in long, complex signals caused by the introduction or growth of damage is to isolate and quantify the difference between baseline and damage signals. Presented here is an overview of efforts to extend coda wave NDE to Carbon-Fiber Reinforced Polymers (CFRP). Experimental results show that coda wave differential features are effective in detecting drilled holes and discriminating between increasing hole diameter and increasing number of holes. The differential features are shown to have an underlying basis function that is dependent on the hole volume and can be scaled by a material dependent coefficient to estimate the feature amplitude and size holes. Measurements were found to be repeatable and three of the features were found to be largely insensitive to noise. The potential for micro-crack detection and monitoring is also demonstrated.

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