A STUDY OF VIBRATION-INDUCED FRETTING CORROSION FOR ELECTRICAL CONNECTORS Except where reference is made to the work of others, the work described in this dissertation is my own or was done in collaboration with my advisory committee. This dissertation does not include proprietary or classified information ________________________________________ Fei Xie Certificate of Approval: ______________________________ ______________________________ George T. Flowers, Co-Chair R. Wayne Johnson, Co-Chair Alumni Professor Ginn Professor Mechanical Engineering Electrical and Computer Engineering ______________________________ ______________________________ Thomas A. Baginski John L. Evans Professor Associate Professor Electrical and Computer Engineering Industry and Systems Engineering _____________________________ Joe F. Pittman Interim Dean Graduate School A STUDY OF VIBRATION-INDUCED FRETTING CORROSION FOR ELECTRICAL CONNECTORS Fei Xie A Dissertation Submitted to the Graduate Faculty of Auburn University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Auburn, Alabama May 10, 2007 A STUDY OF VIBRATION-INDUCED FRETTING CORROSION FOR ELECTRICAL CONNECTORS Fei Xie Permission is granted to Auburn University to make copies of this dissertation at its discretion, upon request of individuals or institutions and at their expense. The author reserves all publication rights. _____________________________ Signature of Author _____________________________ Date of Graduation iii VITA Fei Xie, son of Zuogui Xie and Xiane Zhan, was born on February 5, 1968, in Hubei province, China. He entered the Beijing University of Aeronautics and Astronautics, Beijing, China, in September 1986 and four years later, he graduated with a Bachelor of Science degree in Electrical Engineering. He then worked in Beijing as an electrical engineer at the Institute of Railway Science from July 1990 to March 1993 and Beijing University of Aeronautics and Astronautics from April 1993 to August 1997. He entered the Graduate School of Beijing University of Aeronautics and Astronautics in September 1997 and graduated with a Master of Science degree in Systems Reliability Engineering in May 2000. In May 2002, he entered the Graduate School of Auburn University to work towards the degrees of Master of Science and Doctor of Philosophy in Electrical and Computer Engineering. He married Ying Jiang, daughter of Zixiong Jiang and Guizhi Yan, on April 22, 1997. Fei Xie and Ying Jiang have a son, Ramon P. Xie, who was born in Auburn on March 6, 2002. iv DISSERTATION ABSTRACT A STUDY OF VIBRATION-INDUCED FRETTING CORROSION FOR ELECTRICAL CONNECTORS Fei Xie Doctor of Philosophy, May 10, 2007 (M.S., Auburn University, 2003) (M.S., Beijing University of Aeronautics and Astronautics, 2000) (B.S., Beijing University of Aeronautics and Astronautics, 1990) 188 Typed Pages Directed by George T. Flowers and R. Wayne Johnson Vibration induced fretting degradation is a widely recognized failure phenomenon. However, the basic mechanisms that control the onset and progression of such fretting behavior are not well understood and are a topic of considerable interest in the electrical connector community. In this dissertation, four research projects on this topic are described. The first two projects examined the physical characteristics of vibration-induced fretting corrosion and focused on PC-type connectors and automotive-type connectors respectively. The influence of connector design, wire tie-off length, vibration profile, and lubrication were considered. It was found that both connector designs exhibited self- v consistent relative displacement amplitude thresholds for the onset of fretting corrosion regardless of the excitation frequency. Also, there was a general linear dependency upon the g-level with regard to fretting rates for single frequency excitation. A mathematical model was developed that related the early stage fretting corrosion rate to the threshold vibration levels for the connectors. Additionally, a connector lubricant was tested and observed to inhibit fretting over the amplitude and frequency ranges, as expected. The third project examined the influence of normal force and finish characteristics for vibration-induced fretting degradation. Two finish types and three normal force levels for each finish type were considered, with the objective of determining which created a larger fretting degradation. Once again, a threshold vibration level and a linear fashion resistance change of fretting were found. The relative motion transfer function was also shown to provide a good measure of the tendency to fret. Finally, a comparison of the fretting performance between two commercial connectors was performed as an application of this fretting study. The fourth and final project considered the application of FEA simulation techniques to the prediction of vibration-induced fretting degradation. A single blade/receptacle contact pair was analyzed both experimentally and with an FEA model. The same transfer functions for one type of contact pair were obtained from both simulation and experiment, and the same x-axis relative motions were observed in the simulation when the threshold fretting displacements from the experiment were used. Generally, the results from the simulation matched those from the experiment very well. The results showed that for this limited system, finite element modeling and analysis have great potential for evaluating the influence of design variations on fretting behavior. vi ACKNOWLEDGEMENTS The author would like to express his deep appreciation and sincere thanks to his co-advisors, Dr. George T. Flowers, Department of Mechanical Engineering, and Dr. R. Wayne Johnson, Department of Electrical and Computer Engineering, for their instruction, guidance, encouragement and patience in the completion of this research and dissertation. Their advice has been invaluable and their suggestions and exchanges of ideas have contributed immensely to this dissertation. Thanks are also extended to the other advisory committee members, Dr. Thomas A. Baginski, professor, Department of Electrical and Computer Engineering, and Dr. John L. Evans, associate professor, Department of Industry and Systems Engineering, for their academic guidance, time and generous assistance. The author also thanks his friends, Dr. Roland Horvath and Dr. Xin Hai, for their help during this research. Finally, the author would like to thank his wife, Ying Jiang, and other family members, for their consideration, support and patience during the completion of this degree (Doctor of Philosophy in Electrical and Computer Engineering) at Auburn University. vii Style manual or journal used: Auburn University Guide to Preparation and Submission of Thesis and Dissertation, and Transactions of the Institute of Electrical and Electronics Engineers Computer software used: Microsoft Word 2003, MATLAB 7.0 and ANSYS 9.0 viii TABLE OF CONTENTS LIST OF FIGURES………………………………………………………………….….xiii LIST OF TABLES………………………………………………………………………xix CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW .................................. 1 1.1 Fretting Corrosion..................................................................................................... 1 1.2 Mechanism of Fretting Corrosion............................................................................. 3 1.3 Literature Review of Fretting Corrosion in Electrical Contacts ............................... 4 1.4 Overview of Current Work ..................................................................................... 12 CHAPTER 2 A STUDY OF THE PHYSICAL CHARACTERISTICS OF VIBRATION-INDUCED FRETTING CORROSION............................. 14 2.1 Purpose of This Study............................................................................................. 14 2.2 Description of Experimental Testing...................................................................... 16 2.2.1 Experimental Samples ..................................................................................... 16 2.2.2 Experimental Equipment ................................................................................. 18 2.2.2.1 KEITHLEY Model 2010 Multimeter ....................................................... 19 2.2.2.2 HP 35665A Dynamic Signal Analyzer..................................................... 19 2.2.2.3 POLYTEC Laser Vibrometer ................................................................... 20 2.2.2.4 Vibration System ...................................................................................... 21 2.2.3 Experimental Setup.......................................................................................... 23 2.3 Test Results............................................................................................................. 25 ix 2.3.1 PC Connector................................................................................................... 26 2.3.1.1 Short Tie-off Configuration ...................................................................... 26 2.3.1.2 Middle Tie-off Configuration ................................................................... 29 2.3.1.3 Long Tie-off Configuration ...................................................................... 31 2.3.1.4 Transfer Function and Relative Motion.................................................... 33 2.3.2 Automotive Connector..................................................................................... 39 2.3.2.1 Middle tie-off Configuration....................................................................