MODEL DEVELOPMENT DECISIONS UNDER UNCERTAINTY IN CONCEPTUAL DESIGN A Thesis Presented to The Academic Faculty by Thomas M. Stone In Partial Fulfillment of the Requirements for the Degree Master of Science in the George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology August 2012 MODEL DEVELOPMENT DECISIONS UNDER UNCERTAINTY IN CONCEPTUAL DESIGN Approved by: Dr. Seung-Kyum Choi, Co-Advisor George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Dr. Dirk Schaefer, Co-Advisor George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Dr. Jianxin (Roger) Jiao George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Date Approved: June 21, 2012 To my family for their unconditional love and support ACKNOWLEDGEMENTS First of all, I thank Dr. Seung-Kyum Choi and Dr. Dirk Schaefer for their superb advisement of my research efforts. I could not have asked for better direction and guidance. In only two years, I have matured from amateur research skills to a profound understanding of academic research, and I am confident that our future endeavors will be successful and meaningful. In the teaching sphere, I would like to thank them for their supervision of my teaching assistant experience; their professional advice and counsel will prove invaluable in my life. I thank God for the transformation He has wrought in my life. It is an understatement to say that I would not be in this propitious position today without the grace He has shown to me. Also, it is no small thing that God has made His creation with such complexity and given men curious minds, eager to explore the breadth and depth of it. I am so thankful that I can do something with my life that I enjoy. My fundamental desire is that I can bring Glory to Him through Jesus Christ. I would like to thank my colleagues—Daniel Wu and Jiten Patel—for their support and friendship. Also, efforts by undergraduate research students—Justin Brown and Kevin Strike— have been instrumental in my graduate research and teaching experience. Dennis Page has provided great encouragement and friendship as a fellow worker at the Georgia Tech Savannah campus. And my church family and friends—namely, Chris Bond and Kevin Summit—have been instrumental in my personal growth and guidance. Last (but not least), I would like to thank my family. From my father, I acquired a work-ethic—without which I would never be able to complete my Masters studies. My mother has shown unconditional love and support through many years of school and life’s many circumstances. As my brothers have grown, they have become my best friends, and I wish the best for their futures. My extended family has also continually been a source of great support. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ............................................................................................... iv LIST OF TABLES ............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii LIST OF ABBREVIATIONS ............................................................................................. x SUMMARY ................................................................................................................... xi Chapter 1 INTRODUCTION .............................................................................................. 1 1.1 Motivation ................................................................................................................. 1 1.2 Research Question 1 and Hypothesis ........................................................................ 3 1.3 Research Question 2 and Hypothesis ........................................................................ 4 1.4 Research Question 3 and Hypothesis ........................................................................ 5 1.5 Thesis Organization .................................................................................................. 6 Chapter 2 BACKGROUND AND STATE-OF-THE-ART ................................................ 8 2.1 Medical Product Packaging Problem ........................................................................ 8 Optimization of Cost and Reliability of Packaging .................................................. 10 Complexities in Packaging Design ........................................................................... 11 2.2 MSD Theory in Impact Analysis ............................................................................ 13 Advantages over Comprehensive FEA Models ........................................................ 15 MSD Impact Modeling Techniques .......................................................................... 16 MSD Impact Applications ........................................................................................ 19 2.3 Model Development Background ........................................................................... 20 Categories of Model Development ........................................................................... 20 Types of Uncertainty ................................................................................................. 21 Motivating Example .................................................................................................. 24 2.4 Research Gaps in Model Development................................................................... 33 Model Development in Conceptual Design Phase .................................................... 37 Multiple Sources of Information ............................................................................... 39 ‘Structural’ Model Development and Model Dependencies..................................... 39 Scope of this Work .................................................................................................... 41 Chapter 3 PROPOSED METHODOLOGY ..................................................................... 43 3.1 Drop Test Modeling ................................................................................................ 43 Model Assumptions and Development ..................................................................... 44 Proposed Spring/Damper Models ............................................................................. 45 Multiple Collision Modeling ..................................................................................... 48 Experimental Methods .............................................................................................. 53 Model Parameter Estimation Methodology .............................................................. 60 3.2 Proposed Framework for Model Development Decisions ...................................... 66 Chapter 4 ENGINEERING APPLICATION.................................................................... 74 v 4.1 Model Development Problem ................................................................................. 76 Preliminary Models ................................................................................................... 76 Required Experimentation ........................................................................................ 77 Problem Statement .................................................................................................... 78 4.2 Framework Demonstration ..................................................................................... 79 Chapter 5 CONCLUSIONS AND FUTURE WORK ...................................................... 96 5.1 Research Question 1 and Hypothesis ...................................................................... 96 5.2 Research Question 2 and Hypothesis ...................................................................... 97 5.3 Research Question 3 and Hypothesis ...................................................................... 98 5.4 Limitations .............................................................................................................. 98 Selecting Bounds based on Preliminary Experimentation Results ........................... 98 Development of Objective Function ......................................................................... 99 5.5 Potential Future Work ............................................................................................. 99 Variability and Comprehensive Accuracy Metric .................................................... 99 Embodiment Design .................................................................................................. 99 5.6 Closing Remarks ................................................................................................... 100 REFERENCES ............................................................................................................... 101 vi LIST OF TABLES Page Table 1. Model development and decision-based-design research ................................... 34 Table 2. Model development and decision-based-design research ................................... 35 Table 3. Contact force models .......................................................................................... 52 Table 4. Parameter estimations ......................................................................................... 62 Table 5. Theoretical maximum contact force values ........................................................ 66 Table 6. Preliminary testing results .................................................................................