Guided ultrasonic waves in the tri-layer structures. Application to the non destructive ultrasonic testing of the bonding quality of sheets

Laboratory of control and characterization of materials, Department of Physics, Faculty of Sciences, BP 20, El Jadida, Morocco

Corresponding author: sidkimouncif@hotmail.com

Received: 28 February 2005
Revised: 20 July 2005
Accepted: 29 September 2005
Published online: 14 December 2005

Abstract

This paper presents a study of guided ultrasonic waves in a tri-layer structure composed of two aluminum sheets bonded by an adhesive layer of resin epoxy. Numerical resolution, of high accuracy, of the characteristic equation permitted to determine the dispersion curves and the displacements field in the structure. A new interpretation of the dispersion curves of the tri-layer structure is proposed highlighting the existence, for each propagation mode, of a portion where this mode follows the mode of an adhesive layer and another portion where it follows the mode of an aluminum sheet. From dispersion curves, we determine the displacements field of the tri-layer structure showing that the displacement takes place in the adhesive layer when the mode of propagation is in the first portion and it is dominating in the aluminum sheets if the mode is in the second portion. In addition, we show the possibility of characterization of the quality of bond of the two aluminum sheets from the analysis of dispersion curves of the structure.