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FUNDAMENTAL MECHANISMS AFFECTING FRICTION WELDING UNDER VACUUM By Benedicta Renee Jacoby B.S. Engineering University of California, Berkeley (1985) Submitted to the department of OCEAN ENGINEERING In Partial Fulfillment of the Requirements For the Degrees of MASTER OF SCIENCE IN NAVAL ARCHITECTURE AND MARINE ENGINEERING and MASTER OF SCIENCE IN MECHANICAL ENGINEERING at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June, 1991 © Benedicta Renee Jacoby, 1991 The author hereby grainnttss ttoo MM..II..TT.. ppeerrmmiissssiioonn ttoo rreepprroocduce and to distribute copies of this thesis document in whol)lee or in pan. IAJ6/6 6.1 FUNDAMENTAL MECHANISMS AFFECTING FRICTION WELDING UNDER VACUUM by Benedicta Renee Jacoby Submitted to the department of Ocean Engineering on 10 May 1991 in partial fulfillment of the requirements for the degrees of S.M. Naval Architecture and Marine Engineering and S.M. Mechanical Engineering. ABSTRACT Inertia welding of 2024-T3 aluminum alloy studs to 2024-T3 plate is investigated at atmospheric pressure and under vacuum to determine the effects of vacuum, surface contamination, material, weld force and weld speed on the integrity of the weld. The vacuum conditions are limited to 10 torr or less due to experimental apparatus. The fundamental parameters involved in inertia friction welding are investigated here to lead to the development of a mathematical model for their affects in on-orbit welding in the A construction of a space station. bend test is used to determine a sufficient weld. The special conditions required for on orbit welding are discussed along with a survey of current welding methods and there feasibility and limitations for space station construction. Friction welding, as one of only a few joining techniques that is showing promise for all areas of concern for construction in space : minimal power consumption, ease of automation, minimal operator skill and lack of toxic by products, is discussed in detail prior to the experimental presentation. Thesis Supervisor: Dr. Koichi Masubuchi Title: Professor of Material Science and Ocean Engineering ACKNOWLEDGEMENTS I would like to express my sincere gratitude to the following people: Dr. Koichi Masubuchi forhis support in this effort and enthusiasm in space station construction. Mr. Ravikumar Nagabushanam for his assistance with equipment and knowledge of the "system". Mrs. Carolyn Russel of the Marshall Space Flight Center for her assistance in obtaining suitable materials for testing and her genuine interest. Lt. Michael Smith for his interest and his willingness to explore new ideas. My office mates, Dave Klipp and Ralph Soule, for their curiosity, humor and stimulating conversation. My family and friends, for their continuing support, confidence and inspiration. Lastly, I thank the United States Navy and the Engineering Duty Officer community for giving me the opportunity and financial support to complete my studies here at M.I.T.