Utilization of Oblique Incidence in Acousto-Ultrasonics
The acousto-ultrasonic test technique has proven itself as a very valuable nondestructive evaluation procedure. The technique, however, is severely limited by using normal beam incidence of two transducers side by side. The current theoretical explanation of the wave propagation phenomena in ultrasonic NDE is limited. The purpose of this paper is to explore the full potential of the acousto-ultrasonic technique by way of including oblique incidence, and some theoretical explanation of wave propagation in the structure. By doing this, greater benefit of acousto-ultrasonic nondestructive evaluation can be realized.
Several sample problems that could fit into the category of acoustoultrasonic evaluation are presented and outlined in the paper; the goal being to demonstrate the versatility of the acousto-ultrasonic technique. Four sample problems are covered: An adhesive bond inspection problem involving a single interface considering variations in bond rigidity varying from a smooth to a welded condition. A second problem treats a three layered structure with various boundary conditions. The third problem is associated with composite material inspection examining porosity level and fiber volume fraction variations. The fourth problem considers surface wave techniques in composite material inspection, a modification of which can indeed be considered as an extension of the acousto-ultrasonic test procedure.
KeywordsSurface Wave Critical Angle Lamb Wave Oblique Incidence Plate Wave
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