Nondestructive Evaluation of Adhesive Bonds Using 20 MHz and 25 kHz Ultrasonic Frequencies on Metal and Polymer Assemblies

About the Book

Demands for improvements in aerospace and automotive energy-efficiency, performance, corrosion resistance, body stiffness and style have increased the use of adhesive bonds to help meet those demands, by providing joining technology that accommodates a wider variety of materials and design options. However, the history of adhesive bond performance clearly indicates the need for a robust method of assuring the existence of the required consistent level of adhesive bond integrity in every bonded region. The Quality Assurance of Adhesive Bonds by Ultrasonic Nondestructive Testing technology put forth in this book meets that need by describing two new, complementary ultrasonic techniques for the evaluation of these bonds, and thus provide improvements over previous methods.
The development of a 20 MHz pulse-echo method for nondestructive evaluation of adhesive bonds will accomplish the assessment of bond joints with adhesive as thin as 0.1 mm. This new method advances the state of the art by providing a high-resolution, phase-sensitive procedure that identifies the bond state at each interface of the adhesive with the substrate(s), by the acquisition and analysis of acoustic echoes reflected from interfaces between layers with large acoustic impedance mismatch. Because interface echo amplitudes are marginal when the acoustic impedance of the substrate is close to that of the adhesive, a 25 kHz Lamb wave technique was developed to be employed in such cases, albeit with reduced resolution.
Modeling the ultrasonic echoes and Lamb-wave signals was accomplished using mathematical expressions developed from the physics of acoustic transmission, attenuation and reflection in layered media. The models were validated by experimental results from a variety of bond joint materials, geometries and conditions, thereby confirming the validity of the methodology used for extracting interpretations from the phase-sensitive indications, as well as identifying the range and limits of applications.
Results from the application of both methodologies to laboratory specimens and to samples from production operations are reported herein, and show that bond-joint integrity can be evaluated effectively over the range of materials and geometries addressed.

About the Author

As a Senior Manager for Advanced Materials at DaimlerChrysler (now Chrysler) Corp., Gil led efforts to acquire, develop and implement advances in materials, processes and products for new vehicle development. Previously, as a senior specialist, project engineer and senior research engineer at two automotive manufacturers and NASA, Gil performed research, development, engineering, instruction and technology implementation for improved supersonic propulsion, high-energy fuels, emission spectrochemical analysis, nondestructive evaluation and quality for advanced processes and materials, including light metals, thermoplastics and polymer composites.
His work resulted in implementations, and more than 70 technical publications, book chapters, encyclopedia articles, and about 123 presentations to Conferences and Colloquia, from which Gil has received recognition awards for best paper and outstanding presentations. He has taught college and industrial courses, organized and chaired several international conferences and sessions on advanced materials, quality and automotive composites, chaired and served on several university industrial advisory committees, as well as the Mt. Vernon Academy (Ohio) Board, and was the Martin Luther King Visiting Professor of Physics at Wayne State University.
Gil has a BS in mathematics and chemistry, MS in physics, MBA from the Advanced Management Program at Michigan State University, and a PhD in physics from the University of Windsor. He chaired the local chapters of the Society of Physics Students and Sigma Pi Sigma, and is a fellow in the American Society for Nondestructive Testing, in which he was certified at the highest level in six test methods. He has also held membership in ACS, APS, ASC, ASM, ASNT, CAP, ESD, NTA, SAE, SAS, SME, SPE, AAAS, ASTM and IEEE, and has served as an officer in NTA, SAS, SME, SPE, SPS and ASNT.
Gil and his late wife, Loretta, parented seven children, and he has added three step children with his marriage to wife Betty. His biographical sketch has been published in four Who's Who publications and featured in Ebony's "Speaking of People".