Session: 21-01: Poster Session

Paper Number: 98863

98863 - Inspection of Adhesive Lap Joints Using Non-Linear Fundamental Shear Horizontal Wave Mode 

Adhesive bonds are widely used in aerospace and automobile industries due to their superior strength to weight ratio and stress distribution. Due to their prevalent usage in safety-critical applications, it is crucial to assess the quality of such bonds on a regular basis. The defects in these bonds can be in different forms such as kissing bond, partial bond, and slip bond. The weakening of the interfacial adhesion between the adhesive and the adherent is considered a precursor to defect formation. A non-linear ultrasonic inspection using the fundamental Shear Horizontal (SH0) wave mode is proposed in this work to evaluate the interfacial adhesion. The Periodic Permanent Magnets (PPM) EMAT transducers are used to perform wavelength-constrained SH0 mode excitation and reception over the bonded region. A sandblasted and a non-sandblasted aluminum-epoxy-aluminum tri-layer bonds are prepared to emulate bonds with different interfacial adhesive strengths. It is found that the non-linearity parameter of the SH0 mode is a measure of the adhesive strength of the aluminum-epoxy bond. In comparison to the sand-blasted joint, the nonlinearity parameter of the non-sand-blasted joint has a higher value. Hence measurement of the non-linearity parameter gives a quantitative measure of the strength of adhesion in the lap-shear joint.

Presenting Author: Akhil Balachandran Indian Institute of Technology Madras, India