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The Accuracy and Repeatability of Ultrasonic measurements 6.2 Sensitivity to the Microstructure (Texture) 6.3 The Factors that Affect Ultrasonic Predictions of Plastic Properties 6.3.1 Effects of Coatings 6.3.2 Effects of Accurate Set of Elastic Constants 6.3.3 Effects of Early Truncation of Higher Order ODC's 6.4 Choice of Modeling in Ultrasonic Prediction of Plastic Properties 195 BIBLIOGRAPHY 197 vi ACKNOWLEDGMENTS I am sincerely indebted to my major professor, Dr. R. B. Thompson for providing me an opportunity to work on this challenging and interesting task. He followed my progress with interest and gave me encouragement and valuable guidance throughout this work. I am grateful for his precise and thorough review of this thesis. I would also like to express appre ciations to my co-major professors Drs. Scrutton and Molian for their support of this work. Dr. Scrutton enriched this research with numerous papers published by the previous re searchers in this field. I am grateful for his generous efforts and his input. I would like to extend my appreciations to the members of my graduate committee, Drs. Izworski, Papadakis and Hall. I am indebted to Dr. Izworski for providing me a chance to visit the Dearborn Stamping Plant at Ford Motor Company and his valuable input regarding the prac tical industrial problems in the forming industry. I would also like to thank Dr. Papadakis for many useful discussions regarding the ultrasonic device, Ultra-Form. I am grealty indebted to Dr. Frtitz Reis at LTV Steel Company and Dr. Ming Shi at Na tional Steel Corporation for providing the steel samples and the tensile data. I am also greatful for their most valuable discussions and ideas regarding this research. I would like to express my appreciations to Drs. Okiishi and Bathi in Mechanical Engi neering Department for their financial support of my graduate studies. I would like to thank my wife, Amy, and my children. Aria, Farhad and Lailei for their patience and support. I am indebted to my brother. Dr. Babak Forouraghi, for his constant encouragement throughout this research. Finally, the last but not the least, to my parents, Ali and Homa, whose valuable support and encouragements have been the inspiration behind my graduate studies.

This paper describes the development of an ultrasonic instrument to measure texture (preferred grain orientation), stress, and related physical properties in metal sheets in industrial environments. The technique is based on precise measurements of the speed of guided modes, including angular variations, and is made practical by the use of EMAT transducers, which require no couplant. The instrument is expected to find important initial applications in predicting sheet metal formability, either as a process control tool in the rolling mill or as a quality control tool in a stamping shop.Since the instrument will offer an improved measurement capability not presently available to industry, a much broader range of applications may develop, including measurements of stress and porosity in sheet and other simple geometries.BACKGROUND

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