Adhesive Joint Characterization by Leaky Guided Interface Waves
Ultrasonic inspection of adhesive joints is usually done either by normally incident longitudinal or shear waves or by Lamb modes propagating along the joint, i.e. in the adherend-adhesive-adherend sandwich as a whole. This paper discusses the feasibility of using guided interface waves propagating in the adhesive layer itself for nondestructive evaluation of bond quality. This layer is usually less than 5% of the whole joint, but all defects are expected in this region or on its boundary. True guided interface waves are probably the most sensitive to bond imperfections [1,2], but they are inherently very difficult to generate and detect, therefore we should settle for the second best, namely leaky guided interface waves which lend themselves quite easily to practical applications. The main purpose of this paper is to demonstrate the superior sensitivity of the suggested leaky guided interface wave technique over the more conventional Lamb wave inspection via examples of adhesive joints with different cohesive and adhesive type defects.
KeywordsPorosity Microwave Attenuation Epoxy Compressibility
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