STP972: Damage Assessment by Acousto-Ultrasonic Technique in Composites

    Lorenzo, L
    Postdoctoral research associate and professorProfessor, Center for Composites Research, Washington UniversityPenn State University, St. LouisUniversity Park, MOPA

    Hahn, HT
    Postdoctoral research associate and professorProfessor, Center for Composites Research, Washington UniversityPenn State University, St. LouisUniversity Park, MOPA

    Pages: 18    Published: Jan 1988


    Abstract

    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.

    Keywords:

    composite materials, glass/epoxy, cross-ply laminates, acoustic emission, acousto-ultrasonic technique, damage monitoring, ply cracking, attenuation, wave propagation


    Paper ID: STP26147S

    Committee/Subcommittee: D30.02

    DOI: 10.1520/STP26147S


    CrossRef ASTM International is a member of CrossRef.