Hirsekorn, A. Koka, S. Kurzenhauser, and W Arnold Abstract

The interfaces in bonded structures influence the mechanical behavior of components significantly. Therefore, an important task in nondestructive testing (NOT) is the investigation of the interaction forces in adhesive joints and the development of techniques to evaluate the bond quality. The load capacity of such joints is often limited by regions of weak bonding. As in all materials, the 

Adhesion - Current Research and Application. WulfF Possart Copyright 2005 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-31263-3 

There have been a number of previous attempts to relate the appearance of higher harmonics in the transmission of ultrasound through bonded structures to the quahty of the bonds [2-9]. Commonly used is the so-called nonhnearity parameter y 2, a measure of the generation of only the second harmonic [2], and the distortion factor K which describes the complete nonlinear content of the response [7]. In this paper cahbrated measurements on samples consisting of two aluminum plates joined together by a thin epoxy layer are presented and discussed. The amphtudes and phases of the ultrasonic waves transmitted through the bond are considered. The measurements are related to the results of destructive tensile tests of the adhesive layer. 

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