Table Of Content

MECHANICAL ENGINEERING Introduction to Introduction to Thermodynamics of Thermodynamics of Mechanical Fatigue Mechanical Fatigue Fatigue is probabilistic in nature and involves a complex spectrum of loading history with variable amplitudes and frequencies. Yet most available fatigue failure prediction methods are empirical and concentrate on very specific types of loading. Taking a different approach, Introduction to Thermodynamics of Mechanical Fatigue examines the Microscale treatment of fatigue via the principles of thermodynamics. It starts from the premise that Macroscale fatigue is a dissipative process and must obey the laws of thermodynamics. In general, Plasticity Application it can be hypothesized that mechanical degradation is a consequence of irreversible thermodynamic processes. This suggests that entropy generation offers a natural measure Atomic Scale of degradation. Drawing on recent cutting-edge research and development, the authors present a unified entropic approach to problems involving fatigue. They introduce the fundamentals of fatigue processes and explore a wide range of practical engineering applications. Component Testing The book reviews commonly observed failure modes, discusses how to analyze fatigue problems, and examines the deformation characteristics of a solid material subjected to fatigue loading. It also looks at how to use thermodynamics to determine the onset of fatigue failure. In addition, the book presents methodologies for improving fatigue life and for accelerated fatigue testing. Comprehensive and well organized, this work helps readers apply powerful thermodynamics concepts to effectively treat fatigue problems at the design stage. It offers an accessible introduction to a new and exciting area of research in the field of fatigue failure analysis. Michael M. Khonsari • Mehdi Amiri K14850 ISBN: 978-1-4665-1179-8 90000 9 781466 511798 K14850_Cover_mech.indd 1 7/30/12 3:43 PM Introduction to Thermodynamics of Mechanical Fatigue K14850_Book.indb 1 06/08/12 5:57 PM TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk Introduction to Thermodynamics of Mechanical Fatigue Michael M. Khonsari • Mehdi Amiri Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business K14850_Book.indb 3 06/08/12 5:57 PM CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2013 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20120726 International Standard Book Number-13: 978-1-4665-1180-4 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Dedicated to Karen, Maxwell, Milton, Mason Khonsari, and to the memory of my father (MMK), and to Hassan Amiri K14850_Book.indb 5 06/08/12 5:57 PM TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk Contents Preface ................................................................................................................................xi About the Authors ............................................................................................................xiii Acknowledgments ..............................................................................................................xv Chapter 1 Introduction to Mechanical Degradation Processes ........................................1 1.1 Fatigue ...................................................................................................1 1.2 Fracture ..................................................................................................2 1.3 Wear ......................................................................................................2 1.4 Fretting ..................................................................................................3 1.5 Brinelling and False Brinelling .............................................................4 1.6 Corrosion ...............................................................................................5 1.7 Creep .....................................................................................................5 1.8 Thermal Shock ......................................................................................7 1.9 Impact ....................................................................................................7 References .......................................................................................................9 Chapter 2 Fundamentals of Thermodynamics ...............................................................11 2.1 Open and Closed Systems ...................................................................11 2.2 Equilibrium and Nonequilibrium State ...............................................12 2.3 Steady and Unsteady State ..................................................................14 2.4 Stable and Unstable State ....................................................................15 2.5 First Law of Thermodynamics ............................................................15 2.6 Second Law of Thermodynamics ........................................................21 2.7 Entropy Flow and Entropy Generation ................................................22 2.8 Entropy Balance Equation ..................................................................24 References .....................................................................................................27 Chapter 3 Degradation–Entropy Generation (DEG) Theorem ......................................29 3.1 Thermodynamic Forces and Flows .....................................................30 3.1.1 Examples of Thermodynamic Forces and Flows ....................34 3.2 Relations between Thermodynamic Forces and Flows .......................34 3.2.1 Thermodynamic Orthogonality Principle ...............................38 3.2.2 Coupling between Plastic Deformation and Heat Flow ...........41 3.3 Degradation–Entropy Generation Theorem ........................................42 3.3.1 Degradation Forces and Flows ................................................43 3.3.2 Generalization: DEG Corollary ..............................................44 3.3.3 Application: Paris–Erdogan Law .............................................45 References .....................................................................................................47 vii K14850_Book.indb 7 06/08/12 5:57 PM viii Contents Chapter 4 Fatigue Mechanisms: An Overview ..............................................................49 4.1 Multiscale Characteristics of Fatigue ..................................................49 4.2 Parameters Influencing Fatigue and Classification of Regimes ...........49 4.2.1 Low-Cycle Fatigue (LCF) and High-Cycle Fatigue (HCF) .....50 4.2.2 Effect of Mean Stress ..............................................................56 4.2.3 Load History ............................................................................59 4.2.4 Stress-State: Torsion, Tension–Compression, Bending, and Combined Mode ...............................................................61 4.3 Fatigue and Energy Dissipation ...........................................................63 4.3.1 Micro/Nanoscale Mechanism of Energy Dissipation ..............63 4.3.2 Macroscale Mechanism of Energy Dissipation .......................65 4.3.3 Prediction of Fatigue Failure Based on Energy Dissipation ....65 4.4 Fatigue–Temperature Rise ...................................................................67 4.4.1 Temperature Evolution during Fatigue ....................................67 4.4.2 Application to Prediction of Fatigue Failure ...........................74 References .....................................................................................................78 Chapter 5 Basic Thermodynamic Framework for Fatigue Analysis ..............................83 5.1 Entropy Balance Equation of a Deformed Body .................................86 5.2 Entropy Change Due to Thermal Deformation ...................................91 5.3 Clausius–Duhem Inequality ................................................................95 5.4 Thermodynamic Forces and Flows in Processes Involving Fatigue ......97 5.4.1 Legendre–Fenchel Transformation ..........................................99 References ...................................................................................................100 Chapter 6 Thermodynamic Assessment of Fatigue Failure .........................................103 6.1 Limitation of Conventional Methods and the Need for Further Advances ...........................................................................................103 6.2 Evaluation of Entropy Generation and Entropy Flow ........................103 6.3 Time to Failure ..................................................................................107 6.3.1 Failure Criterion Based on Accumulation of Entropy Generation .............................................................................108 6.3.2 Coffin–Manson Equation and FFE........................................110 6.3.3 Fast Prediction of Fatigue Failure ..........................................111 References ...................................................................................................113 Chapter 7 Damage Mechanics: An Entropic Approach ...............................................115 7.1 Introduction to Damage Mechanics ...................................................115 7.1.1 Entropy-Based Damage Variable ...........................................116 7.2 Continuum Damage Mechanics (CDM) ............................................120 7.2.1 Damage Variable, D( ) ..........................................................121 n 7.2.2 CDM and Fatigue Damage ....................................................123 7.2.3 CDM and Fretting Fatigue .....................................................124 7.2.4 CDM and Sliding Wear .........................................................124 References ...................................................................................................126 K14850_Book.indb 8 06/08/12 5:57 PM Contents ix Chapter 8 Self-Organization in Fatigue .......................................................................129 8.1 Introduction to Self-Organization ......................................................129 8.2 Effect of Electric Current on Fatigue Life .........................................132 8.3 Effect of Magnetic Field on Fatigue Life ...........................................133 8.4 Effect of Environment (Surface Cooling) on Fatigue Life ................133 8.5 Self-Organization and Complexity ....................................................134 References ...................................................................................................135 Chapter 9 Entropic Fatigue: In Search for Applications ..............................................139 9.1 Application to Variable-Loading Amplitude and Structural Health Monitoring .............................................................................139 9.2 Accelerated Fatigue Testing ...............................................................141 9.3 Concluding Remarks .........................................................................144 References ...................................................................................................145 Index ................................................................................................................................147 K14850_Book.indb 9 06/08/12 5:57 PM