EVALUATING aluminum bonds

Adhesively joined aluminum alloy sheets present challenges that steel-adhesive joints do not. Ford researchers present a modified technique to inspect Al-adhesive joints in lab and production environments.

Adhesive bonding technology has gained ever-increasing significance in the automotive industry, especially with the growing use of aluminum (Al) alloy body structures. The variability in thicknesses of the metal and adhesive layers, as well as in joint geometry, of automotive components has presented challenges in nondestructive evaluation of adhesive joints.

Though these challenges were recently overcome for steel-adhesive joints using an ultrasonic pulse-echo technique, the difference in acoustic impedances of steel and Al leads to a lack of robustness in utilizing the same algorithm for Al-adhesive joints. Researchers from Ford Motor Co. and the Institute for Diagnostic Imaging Research employed a modified version of this technique to inspect Al-adhesive joints in both laboratory and production environments.