IMPACT RESPONSE OF STRENGTHENED GLASS WITH ULTRAHIGH RESIDUAL COMPRESSIVE STRESSES By PHILLIP A. JANNOTTI A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2015 © 2015 Phillip A. Jannotti To my hero ACKNOWLEDGMENTS Thanks to my family and friends for their support during my graduate studies, without which my time as a graduate student would not be have been as enjoyable. A special thanks to my girlfriend, Jen, who put up with me during my time here at Florida. Through good times and bad, it is with all of your support that I have reached this point in my life. Thanks to my graduate committee, Dr. Ghatu Subhash, Dr. Peter Ifju, Dr. Nagaraj Arakere, and Dr. John Mecholsky, for their time and attention reviewing my work. Their insight and suggestions have been invaluable to my research. I would like to especially express gratitude to my advisor, Dr. Ghatu Subhash. I sincerely appreciate everything you have done for me, for reading and re-reading every manuscript revision, and for watching and re-watching every presentation. I truly appreciate the countless hours you have invested in me. This research was made with Government support under and awarded by DOD, AirForce Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a, and by Saxon Glass Technologies. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................8 ABSTRACT ...................................................................................................................................11 CHAPTER 1 INTRODUCTION ..................................................................................................................13 Strengthened Glasses ..............................................................................................................13 Applications ............................................................................................................................14 Characterization ......................................................................................................................14 Aims ........................................................................................................................................15 2 TRANSPARENT MATERIALS ............................................................................................19 History ....................................................................................................................................19 Glass .......................................................................................................................................20 Glass Strengthening ................................................................................................................20 3 RESIDUAL STRESS DISTRIBUTION ................................................................................26 Background .............................................................................................................................26 Materials .................................................................................................................................27 Experimental Method .............................................................................................................28 Results and Discussion ...........................................................................................................30 Conclusions.............................................................................................................................35 4 STATIC AND DYNAMIC INDENTATION RESPONSE ...................................................41 Background .............................................................................................................................41 Materials .................................................................................................................................42 Experimental Method .............................................................................................................43 Results and Discussion ...........................................................................................................46 Surface Indentation Hardness ..........................................................................................46 Indentation Damage Evolution ........................................................................................49 Subsurface Indentation Hardness Variation ....................................................................52 Subsurface Indentation Damage ......................................................................................57 Conclusions.............................................................................................................................58 5 5 IMPACT-INDUCED DAMAGE PROPAGATION MORPHOLOGY .................................69 Background .............................................................................................................................69 Materials .................................................................................................................................70 Residual Stress Distribution ............................................................................................71 Bulk Properties ................................................................................................................71 Results.....................................................................................................................................73 Discussion ...............................................................................................................................81 Conclusions.............................................................................................................................85 6 IMPACT-INDUCED DEFORMATION AND ENERGY DISSIPATION MECHANISMS ......................................................................................................................95 Background .............................................................................................................................95 Materials .................................................................................................................................95 Experimental Method .............................................................................................................96 Results and Discussion ...........................................................................................................97 Impact Damage Evolution ...............................................................................................97 Low velocity impact .................................................................................................98 Moderate velocity impact .........................................................................................99 Summary of the impact damage .............................................................................102 Energy Balance ..............................................................................................................107 Kinetic energy of bar dilation .................................................................................107 Kinetic energy of ejecta ..........................................................................................110 Frictional energy ....................................................................................................112 Energy due to fragmentation ..................................................................................113 Elastic wave energy ................................................................................................115 Other .......................................................................................................................116 Summary of the energy balance .............................................................................117 Conclusions...........................................................................................................................117 7 SUMMARY ..........................................................................................................................128 Residual Stress ......................................................................................................................128 Properties ..............................................................................................................................128 Impact Response ...................................................................................................................129 Future Work ..........................................................................................................................130 High Compression, Low Case-Depth Strengthened Glasses ........................................130 Raman Spectroscopy .....................................................................................................131 APPENDIX: ELASTIC WAVE