Recent Advances in the Application of Leaky Lamb Waves to the Nondestructive Evaluation of Adhesive Bonds

In earlier work, the feasibility of applying the Leaky Lamb Wave (LLW) method to the nondestructive evaluation (NDE) of bonded rubber/metal structures was demonstrated. The capability of LLWs to detect and delineate flaws at the bond line was proven, even when the adherends remain in intimate contact. However, variations in adherend properties, surface orientation and thickness can adversely affect detection of bond flaws and assessment of bond quality. In this paper, parameters which degrade both LLW sensitivity and resolution to bond flaws are discussed. Examples of the effects of cold work, thickness change and specimen tilt are presented along with bond flaw detection and characterization results. Also, advances in the theory of bond flaw NDE by LLWs are presented.