Porosity Measurement in Carbon Fiber Epoxy Laminates by Using Acoustography

In this research, the through-transmission Acoustography NDE method was employed to measure porosity in Carbon fiber epoxy composite laminates. The study employed a test specimen with porosity ranging from ≤ 1 % up to 5%. The Acoustography method, operating at around 5 MHz, was easily able to detect and quantify porosity in the test composite laminate. For the validation, the Acoustography results were compared with conventional ultrasonic testing and infrared thermography methods. The Acoustography results were found to be in good agreement with the ultrasonic and thermography methods. It was also demonstrated that there appears to be an approximately linear relationship of ultrasonic attenuation with increasing porosity content. The ultrasonic absorption coefficient showed an increasing trend from 1.5 dB/mm to 2.6 dB/mm with increasing porosity content. This is a very significant finding because Acoustography is being developed as a fast alternative to traditional ultrasonic inspection of composites, and porosity is an important anomaly to be detected in composites.

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