Ultrasonic Evaluation of Adhesive Coverage in Bonded Joints using a 2D Array Technique.

An ultrasonic nondestructive technique capable of robust evaluation of adhesive coverage in bonded metal sheets is presented. Several signal processing techniques for detecting the presence of adhesive between the sheets using pulse-echo data from joints are analyzed. It is shown that an algorithm based on the energy of the reflected waveform weighted within a certain time gate is an efficient and robust parameter for discrimination between adhesion and no adhesion areas. This algorithm was applied using a matrix array of small flat ultrasonic transducers for 2D visualization of adhesive distribution under the metal sheet and estimation of bond width. The developed technique has been successfully tested in laboratory and industrial environments. Accuracy of the adhesive width measurements, conducted in automotive plants on production parts, was shown to be 9 6% in matching the teardown measurements within 1 mm. [ABSTRACT FROM AUTHOR]