Acousto-Ultrasonic Method for the Detection of Adhesive Bond Integrity

Composite materials find increasing importance as structural materials for modern lightweight and low cost aircraft. Structures using composite materials essentially rely on the integrity of adhesive bonds for their structural stability. A major limitation in employing composites in critical structures is that the existing methods of testing the integrity of structures are not adequate to assure the reliability of structures. A nondestructive inspection (NDI) approach using the acousto-ultrasonic method promises several unique features for detecting the loss of adhesion in composite materials. However, the NDT industry has not yet evolved a commercial unit to exploit the exclusive advantages of acousto-ultrasonics in testing composite laminates. The proposed Phase I developmental effort will examine the suitability of the technique, for the detection of the loss of adhesion, in composite structures and will evolve methodology suitable for testing composites. The effort will focus on the computation of propagation of different modes of sound that will commonly be encountered in composite structures, both with and without defects, and will compare with the measured acousto-ultrasonic signals on such structures. We plan to develop a compact and portable test instrument at the end of the Phase II efforts.