Preface ........................................................ XI
Acknowledgments ................................................ XX
About the Author ............................................. XVII
1 Applications throughout the World ............................ 1
1.1 Introduction ............................................ 1
1.2 Large Wind: Blades and Rotors ........................... 1
1.2.1 Key Blade and Rotor Manufacturing Challenges ..... 2
1.3 How Wind Turbines Work .................................. 2
1.3.1 Types of Wind Turbines ........................... 5
1.3.2 Sizes of Wind Turbines ........................... 5
1.3.3 Inside the Wind Turbine .......................... 5
1.3.4 Contradictory Goals .............................. 7
1.3.5 Smooth and Continuous Development ................ 7
1.4 Market for Wind Turbine Composites ...................... 8
1.4.1 Introduction ..................................... 8
1.4.2 Weight and Cost .................................. 8
1.4.3 Technology Evaluation ............................ 9
1.4.4 Market and Turbine Components Material Data ...... 9
1.4.4.1 Wind Energy Market Dynamics ............. 9
1.4.4.2 About Owens Corning .................... 10
1.4.4.3 Wind Turbine Database .................. 10
1.4.5 Components Development Trends ................... 11
1.4.5.1 Rotor Blades ........................... 11
1.4.5.2 Gear Boxes ............................. 11
1.4.5.3 Nacelles ............................... 13
1.4.5.4 Towers ................................. 13
References ............................................. 13
2 Design Wind Power Turbine ................................... 15
2.1 Introduction ........................................... 15
2.2 New Design Concept ..................................... 16
2.3 Rotor Design ........................................... 17
2.4 Transmission for Wind Turbine Blades ................... 19
2.5 Blades Design .......................................... 23
2.5.1 Theoretical Investigation ....................... 23
2.5.2 Experimental Investigation ...................... 26
2.6 Power Control of Wind Turbines ......................... 27
2.6.1 Pitch-Controlled Wind Turbines .................. 27
2.6.2 Hydraulic Pitch Control ......................... 27
2.6.3 Stall-Controlled Wind Turbines .................. 28
2.6.4 Active Stall-Controlled Wind Turbines ........... 28
2.6.5 Individual Pitch Control ........................ 29
2.6.6 Other Power Control Methods ..................... 29
2.7 Wind Turbine Components ................................ 29
2.7.1 History ......................................... 30
2.7.2 Components ...................................... 31
2.7.2.1 Gearbox ................................ 31
2.7.2.2 Gear Rim and Pinions ................... 31
2.8 Proposal for Robust Redesign Turbine Blades ............ 32
2.8.1 Introduction .................................... 32
2.8.2 Loads Acting Outside Wind Turbine Blades ........ 32
2.8.3 The Automatic 3-Axial Braiding Process .......... 33
2.8.4 Pultrusion Process .............................. 34
2.8.5 Shell Curing Mold Prepreg Process ............... 36
2.9 Minimizing the Optimal Number of Shear Webs (Spars)
and Their Placement .................................... 37
2.9.1 Introduction .................................... 37
2.9.2 Shear Web Analysis .............................. 39
2.9.3 Conclusions ..................................... 46
2.10 Skin Stiffness and Thickness Blade Calculation ......... 46
2.10.1 Introduction .................................... 46
2.10.2 Stiffness Calculation ........................... 47
2.10.3 Skin Thickness Calculation of Blades ............ 47
2.10.3.1 Experimental Results ................... 49
2.11 Deflection of Wind Hybrid Blades ....................... 50
2.11.1 Experimental Investigation ...................... 53
2.11.2 Conclusion ...................................... 53
References ............................................. 53
3 Materials for Turbine Power Blades, Reinforcements, and
Resins ...................................................... 55
3.1 Materials Requirements ................................. 55
3.2 Structural Composite Material .......................... 56
3.3 Resins Advantages: Low Viscosity and Low Curing Time ... 61
3.4 Rapid Curing Resin System .............................. 62
3.5 Reinforced Material: Carbon Fiber and Glass Fiber
Fabrics ................................................ 66
3.5.1 Carbon Fibers ................................... 66
3.5.2 Twill Weave Kevlar® ............................. 66
3.5.3 S2-Glass ........................................ 67
3.5.4 E2-Glass ........................................ 68
3.5.5 Gel Coat ........................................ 69
3.6 Core Materials: Honeycomb Sandwich Structures and
Adhesives .............................................. 70
3.6.1 Introduction .................................... 70
3.6.2 Core Materials .................................. 70
3.7 Material Promises a Better Blade Resistance to Wear
and Tear ............................................... 74
3.7.1 Owens Coming's Ultrablade Fabric Solutions ...... 74
3.7.2 Film Layer Protects Wind Turbine Blades
against Electromagnetic Fields .................. 75
3.7.3 Painting of Wind Turbines ....................... 75
3.8 Field Study of Wind Turbine Blade Erosion .............. 76
3.8.1 Introduction .................................... 76
3.8.2 Field Study and Maintenance ..................... 76
3.8.3 Polybutadiene Resins ............................ 77
3.8.3.1 Hydroxyl Functionality ................. 77
3.8.3.2 Hydrolytic Stability ................... 78
3.8.3.3 High Hydrophobicity .................... 78
3.8.3.4 Low Temperature Flexibility ............ 79
3.8.3.5 Adhesion Properties .................... 80
3.8.4 AIRTHANE PET-91 A-Based Elastomers .............. 80
3.8.5 Conclusion ...................................... 81
3.9 Rheological Behavior of Flow Resins .................... 81
3.9.1 Introduction .................................... 81
3.9.2 Viscosity ....................................... 82
3.9.3 Effect of Styrene Contents ...................... 82
3.9.4 Effect of Temperature ........................... 83
3.9.5 Effect of Molecular Weight ...................... 84
3.9.6 Relations between the Viscosity, Processing,
Temperature, and Glass Transition Temperature ... 85
References .................................................. 87
4 Manufacturing Technologies for Turbine Power Blades ......... 89
4.1 Introduction ........................................... 89
4.2 Wet Hand Lay-Up Process ................................ 89
4.3 Filament Winding ....................................... 90
4.4 Prepreg Technology ..................................... 92
4.5 Resin Infusion Technology .............................. 93
4.6 Out-of-Autoclave Composite Prepreg Process ............. 94
4.6.1 Introduction .................................... 94
4.6.2 Curing Laminates without Autoclave .............. 95
4.6.3 Select Technological Parameters and Cure
Conditions ...................................... 96
4.7 Developing Technology for Robust Automation Winding
Process ................................................ 98
4.7.1 Introduction .................................... 98
4.7.1.1 Fiber Placement Process ................ 98
4.7.1.2 Continuous Molding Prepreg Process ..... 99
4.8 Infusion Molding Process .............................. 100
4.8.1 Introduction ................................... 100
4.8.2 Conclusion ..................................... 106
4.9 Rotational Molding .................................... 106
4.9.1 Introduction ................................... 106
4.9.2 History ........................................ 106
4.9.3 Equipment and Tooling .......................... 107
4.9.4 Standard Setup and Equipment for Rotational
Molding ........................................ 108
4.9.4.1 Rock and Roll Rotating Molding
Machines .............................. 108
4.9.4.2 Clamshell Machine ..................... 108
4.9.4.3 Vertical or Up and Over Rotational
Machine ............................... 108
4.9.4.4 Shuttle or Swing Arm Machine .......... 108
4.9.4.5 Carousel Machine ...................... 109
4.9.5 Production Process ............................. 109
4.9.6 Recent Improvements ............................ 110
4.9.7 Mold Release Agents ............................ 111
4.9.8 Materials ...................................... 111
4.9.8.1 Natural Materials ..................... 112
4.9.9 Products ....................................... 112
4.9.9.1 Product Design ........................ 112
4.9.9.2 Designing for Rotational Molding ...... 113
4.9.9.3 Material Limitations and
Considerations ........................ 113
4.9.9.4 Wall Thickness ........................ 113
4.9.10 Process: Advantages, Limitations, and Material
Requirements ................................... 114
4.9.10.1 Limitations ........................... 115
4.9.11 Conclusions .................................... 115
References ............................................... 115
5 Dynamic Strength ........................................... 119
5.1 Stress and Vibration Analysis of Composite Wind
Turbine Blades ........................................ 119
5.1.1 Introduction ................................... 119
5.2 Stress Analysis of Propeller Blades ................... 119
5.3 Theoretical Investigation ............................. 121
5.4 Vibration Analysis .................................... 126
5.5 Experimental Analysis ................................. 132
5.5.1 Conclusions .................................... 134
5.6 Mechanical Measurements Deformations in Hybrid
Turbine Blades ........................................ 134
5.6.1 Introduction ................................... 134
5.6.2 Strain-Stress Relation ......................... 135
5.7 Mechanical and Thermal Properties ..................... 137
5.7.1 Introduction ................................... 137
5.7.2 History of Investigating Mechanical
Properties ..................................... 138
5.7.3 Testing Mechanical and Thermal Properties of
the Prepreg Laminates .......................... 139
5.7.4 Conclusions .................................... 139
5.8 Fatigue Strength and Weibull Analysis ................. 141
5.8.1 Introduction ................................... 141
5.8.2 Fatigue Strength Prediction .................... 141
5.8.3 Static and Dynamic Fatigue Strength ............ 146
5.8.4 Experimental Investigation ..................... 147
5.8.5 Concluding Remarks ............................. 149
5.9 Dynamic Analysis: Fourier Function for Prediction of
Fatigue Lifecycle Test ................................ 150
5.9.1 Introduction ................................... 150
5.9.2 Theoretical Investigation ...................... 151
5.9.3 Experimental Investigation ..................... 152
5.9.4 Conclusion ..................................... 154
5.10 Simulating Dynamics, Durability, and Noise Emission
of Wind Turbines ...................................... 154
5.10.1 Introduction ................................... 154
5.10.2 Engineering Challenges ......................... 154
5.10.3 An Integrated Simulation Process ............... 155
5.10.4 Multibody Simulation to Assess Dynamic
Behavior ....................................... 155
5.10.5 Optimizing Overall Durability Performance ...... 157
5.10.6 Complying with Noise Regulations ............... 158
5.10.7 Optimizing the Overall Wind Turbine System
Behavior ....................................... 158
5.10.8 Conclusions .................................... 160
References ............................................ 160
6 NDE Digital Methods for Predicting Stiffness and
Strength of Wind Turbine Blades ............................ 163
6.1 Ultrasonic Nondestructive Method to Determine
Modulus of Elasticity of Wind Turbine Blades .......... 163
6.1.1 Introduction ................................... 163
6.1.2 Theory and Application of Ultrasonic Method .... 163
6.1.3 Conclusions .................................... 171
6.2 Dynamic Local Mechanical and Thermal Strength
Prediction Using NDT for Material Parameters
Evaluation of Wind Turbine Blades ..................... 172
6.2.1 Introduction ................................... 172
6.2.2 Experimental Investigation Results ............. 178
6.2.3 Concluding Remarks ............................. 180
6.3 Noncontact Measurement of Delaminating Cracks
Predicts the Failure in Hybrid Wind Turbine Blades .... 181
6.3.1 Introduction ................................... 181
6.3.2 Damage Mechanisms of Failure ................... 181
6.3.3 Temperature Measurement of the Surface of an
FRP ............................................ 183
6.3.4 Fatigue Strength Improvement ................... 185
6.3.5 Conclusions .................................... 185
6.4 Nondestructive Inspection Technologies for Wind
Turbine Blades ........................................ 186
6.4.1 Introduction ................................... 186
6.4.2 Measurement Concept ............................ 187
6.4.3 Application of the PSP/TSP Technique ........... 187
6.4.4 Luminescent Paint Control ...................... 190
6.4.5 Experimental Investigation ..................... 193
6.4.6 Concluding Remarks ............................. 195
References ............................................ 195
7 Aerodynamic Structural Noise ............................... 199
7.1 Introduction .......................................... 199
7.2 Wind Turbine Aerodynamics ............................. 199
7.2.1 Axial Momentum and the Betz Limit .............. 199
7.3 Measuring Wind Turbine Noise .......................... 203
7.4 Reduce Noise in Wind Turbine Blades ................... 203
7.5 Sound Emissions, Temperature and Pressure ............. 207
7.5.1 Density, Temperature, and Pressure
Correlation .................................... 208
7.5.2 Water Vapor .................................... 208
7.6 Offshore Support Structures for Power Wind Turbine
Blades ................................................ 211
7.6.1 Introduction ................................... 211
7.6.1.1 Support Structure Design .............. 211
7.6.2 Conclusion ..................................... 212
7.6.3 Offshore Wind Initiative ....................... 212
References ............................................ 217
Index ......................................................... 219
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