title: Propagation of ultrasonic guided waves in lap-shear adhesive joints: case of incident a0 Lamb wave.
abstract: This paper deals with the propagation of ultrasonic guided waves in adhesively bonded lap-shear joints. The topic is relevant to bond inspection by ultrasonic testing. Specifically, the propagation of the lowest-order, antisymmetric a0 mode through the joint is examined. An important aspect is the mode conversion at the boundaries between the single-plate adherents and the multilayer overlap. The a0 strength of transmission is studied for three different bond states in aluminum joints, namely a fully cured adhesive bond, a poorly cured adhesive bond, and a slip bond. Theoretical predictions indicate that the dispersive behavior of the guided waves in the multilayer overlap is highly dependent on bond state. Experimental tests are conducted in lap-shear joints by a hybrid, broadband laser/air-coupled ultrasonic setup in a through-transmission configuration. The Gabor wavelet transform is employed to extract energy transmission coefficients in the 100 kHz 1.4 MHz range for the three different bond states examined. The cross-sectional mode shapes of the guided waves are shown to have a substantial role in the energy transfer through the joint.
authors.affiliation: NDE & Structural Health Monitoring Laboratory, Department of Structural Engineering, University of California, San Diego, 9500 Gilman Drive, M. C. 0085, La Jolla, California 92093-0085, USA. flanza@ucsd.edu
authors.forename: Francesco
authors.initials: F
authors.lastname: Lanza di Scalea
authors.forename: Piervincenzo
authors.initials: P
authors.lastname: Rizzo
authors.forename: Alessandro
authors.initials: A
authors.lastname: Marzani