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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

ASSESSMENT OF RESEARCH NEEDS FOR WIND TURBINE ROTOR MATERIALS TECHNOLOGY

Committee on Assessment of Research Needs for Wind Turbine Rotor Materials Technology

Energy Engineering Board

Commission on Engineering and Technical Systems

National Research Council

NATIONAL ACADEMY PRESS
Washington, D.C.
1991

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Frank Press is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Samuel O. Thier is the president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council.

This report and the study on which it is based were supported by Contract No. DE-AC04-89AL58181 between the U.S. Department of Energy and the National Academy of Sciences-National Research Council.

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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

COMMITTEE ON ASSESSMENT OF RESEARCH NEEDS FOR WIND TURBINE ROTOR MATERIALS TECHNOLOGY

GEORGE E. DIETER (Chairman), Dean,

College of Engineering, University of Maryland, College Park, Maryland

JAMIE CHAPMAN, Power Systems Consultant,

Boston, Massachusetts

H. THOMAS HAHN,

Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania

DEWEY H. HODGES,

School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, Georgia

CHARLES W. ROGERS,

Bell Helicopter Textron, Inc., Fort Worth, Texas

LENA VALAVANI,

Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts

MICHAEL D. ZUTECK, Consultant,

Kemah, Texas

National Research Council Staff

KAMAL J. ARAJ, Study Director,

Energy Engineering Board

THERESA A. FISHER, Study Assistant (to April 1990)

JAN C. KRONENBURG, Study Assistant (to February 1991)

ENERGY ENGINEERING BOARD

JOHN A. TILLINGHAST (Chairman),

Tiltec, Portsmouth, New Hampshire

DONALD B. ANTHONY,

Bechtel Corporation, Houston, Texas

RICHARD E. BALZHISER,

Electric Power Research Institute, Palo Alto, California

BARBARA R. BARKOVICH, Barkovich and Yap, Consultants,

San Rafael, California

JOHN A. CASAZZA, CSA Energy Consultants,

Arlington, Virginia

RALPH C. CAVANAGH,

Natural Resources Defense Council, San Francisco, California

DAVID E. COLE,

University of Michigan, Ann Arbor, Michigan

H. M. (HUB) HUBBARD,

Midwest Research Institute (retired), Golden, Colorado

ARTHUR E. HUMPHREY,

Lehigh University, Bethlehem, Pennsylvania (to February 1991)

CHARLES IMBRECHT,

California Energy Commission, Sacramento, California

CHARLES D. KOLSTAD,

University of Illinois, Urbana, Illinois

HENRY R. LINDEN,

Gas Research Institute, Chicago, Illinois

JAMES J. MARKOWSKY,

American Electric Power Service Corporation, Columbus, Ohio (to February 1991)

SEYMOUR L. MEISEL,

Mobile R&D Corporation (retired), Princeton, New Jersey

DAVID L. MORRISON,

The MITRE Corporation, McLean, Virginia

MARC H. ROSS,

University of Michigan, Ann Arbor, Michigan

MAXINE L. SAVITZ,

Garrett Ceramic Component Division, Torrance, California

HAROLD H. SCHOBERT,

Pennsylvania State University, University Park, Pennsylvania

GLENN A. SCHURMAN,

Chevron Corporation, San Francisco, California

JON M. VEIGEL,

Oak Ridge Associated Universities, Oak Ridge, Tennessee

BERTRAM WOLFE,

GE Nuclear Energy, San Jose, California

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

Staff

ARCHIE L. WOOD, Executive Director,

Commission on Engineering and Technical Systems, and

Director,

Energy Engineering Board (to January 1991)

MAHADEVAN (DEV) MANI, Director, Energy Engineering Board

KAMAL J. ARAJ, Senior Program Officer

ROBERT COHEN, Senior Program Officer (retired)

GEORGE LALOS, Senior Program Officer

JAMES J. ZUCCHETTO, Senior Program Officer

JUDITH A. AMRI, Administrative/Financial Assistant

THERESA M. FISHER, Administrative Secretary

JAN C. KRONENBURG, Administrative Secretary

PHILOMINA MAMMEN, Administrative Secretary

NANCY WHITNEY, Administrative Secretary

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

PREFACE

Wind-driven power systems represent a renewable energy technology that is still in the early stages of development. These wind power plants installed in the early 1980s suffered structural failures chiefly because of incomplete understanding of the wind forces (especially the turbulence component) acting on these large structures and in some cases because of poor quality in manufacture. Failure of the rotor blades was one of the principal and most serious structural failures. Failures from these causes are now somewhat better understood. Another limitation to economical achievement of the potential of wind energy is uncertainty about the long-term response of wind turbine rotor materials to the turbulent stochastic loadings to which they are subjected. These structures can be subjected to as many as a billion stress cycles.

In accordance with its assessment of its long-term research responsibilities, the Department of Energy requested the National Research Council to assess the research needs for wind turbine rotor technology. Such a study would assist in organizing the information about the current status of wind turbine rotor materials, their manufacture into blades, and their operation and life performance in service. Of special importance was an assessment of current materials technology and design methodologies to provide perspective for future investigations.

The Committee on Assessment of Research Needs for Wind Turbine Rotor Materials Technology was formed by the Energy Engineering Board to specifically evaluate the following issues (see Appendix A for Statement of Task):

  • the adequacy of existing models to predict dynamic stress patterns;

  • the properties of wind turbine materials in dynamic and fatigue failure;

  • understanding of the performance of joints, fasteners, and critical sections in relation to failure modes and fracture;

  • the tools needed to study these phenomena, such as computer design tools, and materials databases;

  • the need for special laboratory facilities, models, and prototypes to improve the design and operation of wind energy systems;

  • the opportunities for new materials to improve wind turbine life; the potential for improved design methods, advanced control techniques, and better manufacturing processes and advanced materials for better performance and longevity.

In addition, the committee took as its responsibility the development, in broad outline, of a research and development program that would place U.S. wind power technology in a preeminent world position.

In carrying out its assignment the committee examined an extensive literature on wind machines and wind turbine rotor materials. The emphasis of the study was on wind machines suitable for utility applications. Many U.S. experts on these subjects briefed the committee in two meetings of two-day duration (see Appendix B). The committee wishes to acknowledge with gratitude the assistance of the following individuals for their time and knowledge:

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

Holt Ashley, Stanford University; Charles Carlson and Marilyn W. Wardle, E.I. duPont de Nemours & Co.; John C. Doyle, California Institute of Technology; Brant Goldsworthy, ALCOA/Goldsworthy Engineering; Richard H. Hilt, Gas Research Institute; William Holley, U.S. Windpower; Donald Hunston, National Institute for Standards and Technology; Edwin T.C. Ing; John Mandell, Montana State University; Robert C. Monroe, Hudson Products; Robert H. Monroe, Gougeon Brothers; Peter Ogle, Dow United Technologies Composite Products; Donald Pederson and Fred J. Policelli, Hercules, Inc.; Lawrence Rehfield, University of California-Davis; Forrest S. Stoddard, Alternative Energy Institute; Robin Whitehead, Northrop; Daniel F. Ancona III, Leonard J. Rogers and Jeffrey H. Rumbaugh, U.S. Department of Energy; James Tangler and Robert Thresher, Solar Energy Research Institute; and Herbert Sutherland, Sandia National Laboratories.

George E. Dieter, Chairman

Committee on Assessment of Research Needs for Wind Turbine Rotor Materials Technology

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

CONTENTS

 

 

LIST OF FIGURES

 

ix

 

 

LIST OF TABLES

 

x

 

 

EXECUTIVE SUMMARY

 

1

1

 

INTRODUCTION

 

5

   

Scope and Content,

 

5

   

Wind-Driven Power Plants,

 

5

   

Why Materials Knowledge Is Critical,

 

8

   

The Evolution of Wind-Driven Power Plants,

 

9

   

The Principal Component: Wind Turbines,

 

12

   

Power Conversion Equations,

 

16

   

The Wind Environment,

 

19

   

Fatigue Cycle Accumulation,

 

20

   

References and Bibliography,

 

23

2

 

STRUCTURAL LOADING CHARACTERISTICS

 

25

   

Load Characterization,

 

26

   

Blade Failure Experience,

 

27

   

Lessons from Helicopter Experience,

 

27

   

Recommendations,

 

32

   

References and Bibliography,

 

33

3

 

MATERIALS PROPERTIES AND LIFE PREDICTION

 

35

   

Fibers,

 

35

   

Matrix Materials,

 

39

   

E-Glass/Plastic Composites,

 

43

   

Fatigue Life Prediction,

 

48

   

Toughness Considerations,

 

49

   

Wood/Epoxy Composites,

 

50

   

Recommendations,

 

60

   

References and Bibliography,

 

61

4

 

WIND TURBINE ROTOR DESIGN

 

67

   

Airfoil Evolution,

 

67

   

Aerodynamic Tip Brakes,

 

69

   

Blade Root Retention,

 

71

   

Glass-Reinforced Plastic (GRP) Blade Roots,

 

71

   

Wood/Epoxy Blade Roots,

 

75

   

Blade Joining,

 

75

   

Blade Design Considerations,

 

76

   

Fiberglass Blades,

 

76

   

Wood/Epoxy Blades,

 

78

   

Recommendations,

 

79

   

GRP,

 

79

   

Wood/Epoxy,

 

79

   

Generic,

 

79

   

References and Bibliography,

 

80

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

LIST OF FIGURES

Figure 1-1

 

Wind power plant in Altamont Pass, California

 

6

Figure 1-2

 

World energy generation by wind power plants during 1989

 

10

Figure 1-3

 

Growth of generating capacity for California wind power plants

 

10

Figure 1-4

 

Growth of annual energy production for California wind power plants

 

12

Figure 1-5

 

Wind turbine subsystems

 

13

Figure 1-6

 

Wind turbine power curve

 

15

Figure 1-7

 

Wind flow field and turbine loads

 

16

Figure 1-8

 

Comparison of logarithmic power in the wind with a wind turbine power curve

 

17

Figure 1-9

 

Wind turbine blade control methods

 

19

Figure 1-10

 

Accumulation of fatigue cycles

 

22

Figure 2-1

 

Process necessary to analyze composite blades

 

29

Figure 3-1

 

Trends of longitudinal tensile fatigue S-N data for unidirectional composites with various fibers

 

38

Figure 3-2

 

Schematics of various fiber preforms

 

39

Figure 3-3

 

Stress-strain relationships of glass/epoxy laminates under uniaxial tension

 

45

Figure 3-4

 

Modes of damage growth in composite laminate under fatigue

 

47

Figure 3-5

 

Laminate directional properties and shear directional nomenclature

 

52

Figure 3-6

 

Wood strength change due to temperature at two moisture conditions

 

55

Figure 3-7

 

Wood moisture content versus atmospheric relative humidity

 

55

Figure 3-8

 

Effect of moisture content on laminate mechanical properties

 

56

Figure 3-9

 

Typical tensile fatigue strength of wood/epoxy laminate

 

56

Figure 3-10

 

Typical compression fatigue strength of wood/epoxy laminate

 

57

Figure 3-11

 

Typical reversed stress fatigue strength of wood/epoxy laminate

 

57

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
×

Figure 4-1

 

Commonly used early HAWT airfoils

 

68

Figure 4-2

 

SERI advanced wind turbine airfoils

 

68

Figure 4-3

 

Nine-meter GRP wind turbine blade

 

70

Figure 4-4

 

Eleven-meter wood/epoxy blade airfoil thickness distribution and planform

 

70

Figure 4-5

 

Flanged GRP blade root design

 

71

Figure 4-6

 

Flanged root design limitation due to steel/GRP strain incompatibility

 

73

Figure 4-7a

 

Bonded steel root tube GRP hub design

 

74

Figure 4-7b

 

Wood/epoxy blade root

 

74

Figure 4-8

 

All-wood/epoxy composite hub

 

76

Figure 5-1

 

UH-1H composite main rotor blade

 

85

Figure 5-2

 

RTM cooling tower blade

 

86

Figure 5-3

 

4BW hingeless bearingless rotor

 

88

Figure 6-1

 

Wind turbine drive train

 

92

LIST OF TABLES

Table 2-1

 

Blade Sectional Analysis Codes

 

30

Table 3-1

 

Typical Properties of Fibers

 

36

Table 3-2

 

Typical Properties of Unidirectional Composites

 

37

Table 3-3

 

Properties of Case Resins

 

41

Table 3-4

 

High-Performance Thermoplastics Used as Matrix Resins

 

43

Table 3-5

 

Trade-offs Between Thermosets and Thermoplastics as Matrices

 

44

Table 3-6

 

Typical Static Strength, Type 110 Laminate

 

53

Table 6-1

 

Control Effectors and Sensors for a Pitch Controlled Wind Turbine

 

92

Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Suggested Citation:"FRONT MATTER." National Research Council. 1991. Assessment of Research Needs for Wind Turbine Rotor Materials Technology. Washington, DC: The National Academies Press. doi: 10.17226/1824.
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Wind-driven power systems represent a renewable energy technology. Arrays of interconnected wind turbines can convert power carried by the wind into electricity. This book defines a research and development agenda for the U.S. Department of Energy's wind energy program in hopes of improving the performance of this emerging technology.

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