Ultrasonic Estimation Of Porosity In Composite Materials Using Acoustic Attenuation

Voids, which considerably degrade mechanical performance, are the most common and dangerous type of flaw found in composite materials. In this study, a smart acoustic attenuation model was proposed to estimate porosity (ie void content) in carbon fibre composite materials. The attenuation model was developed using a priori knowledge, which consisted of determining porosity using a metalloscope and estimating the corresponding acoustic attenuation via ultrasonic testing. A Hilbert transform-based processing method was introduced to process ultrasonic echoes, which were used to compute acoustic attenuation. Several textile glass fibre laminates and unidirectional carbon fibre laminates used in the AVIC Leadair AG300 aircraft (a whole fuselage composite aircraft built in China) were selected as specimens. Experimental results indicated that the porosity estimated using the acoustic attenuation model agreed well with the results obtained using the destructive method of metallography.