SYMPOSIA PAPER Published: 01 January 1988

Damage Assessment by Acousto-Ultrasonic Technique in Composites


This paper addresses the nondestructive evaluation of cross-ply [0/90]2s and [90/0]2s S-2 G1/DER 332 laminates using acousto-ultrasonic (AU) and acoustic emission (AE) techniques. Acoustic emission and acousto-ultrasonic measurements gave early warnings of damage initiation before transverse cracks became visible. AU parameters such as peak amplitude, energy, and stress wave factor were equally sensitive to damage initiation, but peak amplitude and energy were more sensitive to damage accumulation. Variations of peak amplitude, event duration, ringdown counts, and rise time in AU tests were analyzed to show that internal damage not only increased the apparent attenuation but also affected the wave envelope. The same effect was also present in AE tests. Acousto-ultrasonic tests of an undamaged cross-ply laminate showed that the apparent attenuation coefficients were almost independent of the wave propagation direction. The strongest wave was found along the fibers in the ply in contact with the transducers and the weakest wave traveled 45 deg to the fibers.

Author Information

Lorenzo, L
Penn State University, University Park, PA
Hahn, HT
Penn State University, University Park, PA
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Developed by Committee: D30
Pages: 380–397
DOI: 10.1520/STP26147S
ISBN-EB: 978-0-8031-5044-7
ISBN-13: 978-0-8031-0980-3