Contents
Preface ix
Acknowledgments xi
1 Introduction and overview of ceramic-matrix composites 1
1.1 Introduction 1
1.2 Application of ceramic-matrix composites 2
1.2.1 Reinforced fibers 2
1.2.2 Interface phase 2
1.2.3 Ceramic matrix 4
1.2.4 Application in aero engines 4
1.2.5 France 4
1.2.6 United States 6
1.2.7 Japan 8
1.2.8 Application in rocket engines 9
1.2.9 Application in Scramjet Engine 11
1.2.10 Application in thermal protection systems 12
1.3 Overview of tensile behavior of ceramic-matrix composites 14
1.3.1 Experimental observation 16
1.3.2 Theoretical Analysis 25
1.4 Overview of fatigue behavior of ceramic-matrix composites 28
1.4.1 Fatigue hysteresis behavior 31
1.4.2 Interface wear behavior 35
1.4.3 Fibers strength degradation 37
1.4.4 Oxidation embrittlement 37
1.4.5 Modulus degradation 38
1.4.6 The effect of loading frequency 40
1.4.7 The Effect of Stress Ratio 44
1.5 Overview of lifetime prediction methods of ceramic-matrix composites 45
1.5.1 S_N curve 45
1.5.2 Fatigue life prediction 57
1.6 Conclusion 58
References 58
Further reading 73
2 Matrix cracking of ceramic_matrix composites 75
2.1 Introduction 75
2.2 First-matrix cracking in an oxidation environment at elevated temperature 75
2.2.1 Stress analysis 78
2.2.2 Interface debonding 81
2.2.3 Matrix cracking stress 82
2.2.4 Results and discussion 83
2.2.5 Experimental comparisons 86
2.3 Matrix multicracking evolution considering fibers poisson contraction 86
2.3.1 Stress analysis 92
2.3.2 Interface debonding 94
2.3.3 Multiple matrix cracking 95
2.3.4 Results and discussion 96
2.3.5 Experimental comparisons 100
2.4 Matrix multicracking evolution considering interface oxidation 104
2.4.1 Stress analysis 106
2.4.2 Interface debonding 106
2.4.3 Multiple matrix cracking 108
2.4.4 Results and discussion 108
2.4.5 Experimental comparison 115
2.5 Matrix multicracking evolution of cross-ply ceramic_matrix composites 121
2.5.1 Stress analysis 121
2.5.2 Energy balance approach 125
2.5.3 Results and discussion 132
2.6 Conclusion 140
References 140
Further reading 143
3 Tensile strength of ceramic-matrix composites 145
3.1 Introduction 145
3.2 Tensile strength under multiple fatigue loading 149
3.2.1 Stress analysis 151
3.2.2 Damage models 152
3.2.3 Results and discussion 160
3.2.4 Experimental comparisons 163
3.3 Tensile strength under cyclic loading at elevated temperatures in
oxidative environments 166
3.3.1 Residual strength model 170
3.3.2 Results and discussion 172
3.3.3 Experimental comparisons 180
3.4 Conclusion 186
References 186
Further reading 191
4 Interface debonding and sliding of ceramic-matrix composites 193
4.1 Introduction 193
4.2 Interface debonding and sliding under different loading sequences 194
4.2.1 Stress analysis 196
4.2.2 Interface slip lengths 199
4.2.3 Results and discussion 203
4.2.4 Experimental comparisons 221
4.3 Hysteresis dissipated energy under multiple loading sequences 238
4.3.1 Hysteresis theories 240
4.3.2 Results and discussion 242
4.3.3 Experimental comparisons 252
4.4 Conclusion 268
References 270
Further reading 272
5 Damage evolution of ceramic-matrix composites under cyclic
fatigue loading 273
5.1 Introduction 273
5.2 Hysteresis-based damage parameters 276
5.3 Tensile loading_unloading damage evolution 280
5.3.1 Results and discussion 280
5.3.2 Experimental comparisons 293
5.4 Cyclic fatigue damage evolution 306
5.4.1 Results and discussion 309
5.4.2 Experimental comparisons 319
5.5 Static fatigue damage evolution 358
5.5.1 Results and discussion 362
5.5.2 Experimental comparisons 368
5.6 Conclusion 369
References 371
Further reading 374
6 Fatigue life prediction of ceramic-matrix composites based on
hysteresis dissipated energy 375
6.1 Introduction 375
6.2 Theoretical analysis 376
6.3 Results and discussions 378
6.3.1 Effects of fatigue peak stress on fiber_matrix interface
debonding, HDE, and HDE-based damage parameters 379
6.3.2 Effects of fatigue stress ratio on HDE and HDE-based
damage parameters 382
6.3.3 Effects of matrix crack spacing on fiber_matrix interface
debonding, HDE, and HDE-based damage parameters 384
6.3.4 Effects of fiber volume fraction on fatigue life, fiber_matrix
interface debonding, HDE, and HDE-based damage
parameters 391
6.4 Experimental comparisons 398
6.4.1 Unidirectional ceramic-matrix composites 398
6.4.2 Cross-ply ceramic-matrix composites 403
6.4.3 2D ceramic-matrix composites 425
6.4.4 2.5D ceramic-matrix composites 433
6.4.5 3D ceramic-matrix composites 435
6.5 Conclusion 446
References 446
Further reading 451
Index 453
Preface
Ceramic-matrix composites (CMCs) have the advantages of high-temperature resistance, low density, and low-thermal expansion coefficient, which can significantly reduce engine or system structure quality, and improve the temperature-bearing capacity for components used in high temperatures. CMCs have already been applied in aero, rocket, and scramjet engines, thermal protection system, and many others.
Compared to the monolithic ceramic, the mechanical behavior of CMCs has many different characteristics. During the preparation of CMCs, there is microcracking in the matrix. Under cyclic loading, the growth rate of microcracking in the matrix is much slower than that of monolithic ceramic. For monolithic ceramic, the fatigue failure is often caused by single cracking. For CMCs, many cracks appear in the matrix under cyclic loading, which is, however, not the direct cause of fatigue failure. Understanding the failure mechanisms and internal damage evolution represents an important step to ensure the reliability, durability, and safety of CMCs. This book focuses on the durability of fiber-reinforced CMCs at elevated temperatures, especially the damage mechanisms and lifetime, including:
1. Time_stress-dependent damage models for the first matrix cracking and multiple matrix cracking of CMCs at elevated temperatures are developed. The relationships between the first matrix cracking stress, multiple matrix cracking evolution, fiber_matrix interface debonding and oxidation, oxidation time and temperature, and different matrix cracking modes are established.
2. Cyclic_time-dependent strength degradation models at elevated temperatures are developed. The residual strength of different CMCs subjected to cyclic fatigue loading at elevated temperatures are predicted.
3. Cyclic-dependent interface debonding and sliding of CMCs subjected to multiple loading sequences are investigated considering interface wear mechanisms. The relationships between interface debonding and sliding, loading sequence, and applied cycle numbers are established.
4. Hysteresis-based damage evolution models of CMCs subjected to cyclic fatigue loading at elevated temperatures are developed. The relationships between the hysteresis loops, hysteresis dissipated energy (HDE), HDE-based damage parameters, and interface debonding and sliding are established.
5. An energy-based lifetime prediction method of CMCs at elevated temperature is developed. The experimental fatigue lifetime of unidirectional, cross-ply, 2D, 2.5D, and 3D CMCs are predicted for different testing conditions.
I hope this book can help material scientists and engineering designers understand and master the durability mechanisms of CMCs.