WIND BLADE REPAIR. Study Guide

Transcription

1 WIND BLADE REPAIR Study Guide

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3 Wind Blade Repair When you apply to become a Certified Composites Technician-Wind Blade Repair, you take the first step towards achieving excellence in the composites industry, advancing your career, and pursuing comprehensive composites knowledge. The CCT program is designed to elevate standards in the industry by enhancing individual performance and recognizing those who demonstrate critical knowledge of the composites industry. The CCT-WBR designation is a noted symbol of education among employers, employees, and industry professionals. As the industry advances, being a CCT will become increasingly important. If you are committed to developing your career, attaining the CCT-WBR designation will allow others to recognize you as a certified composites industry professional American Composites Manufacturers Association 1

4 Disclaimer The sole purpose of this Study Guide is to assist in the preparation for the CCT examination. It is not a formal code or standard of the American Composites Manufacturers Association nor is the information contained herein based upon such a code or standard. While the Study Guide reflects ACMA s understanding of current industry practices in general, nothing herein should be viewed as a recommendation by ACMA that any application, technique or process is appropriate in any particular circumstance. Similarly, the fact that a particular application, technique or process is listed in the Study Guide should not be viewed as an endorsement by ACMA of such application, technique or process. ACMA makes no claims concerning the accuracy or applicability of the information contained in the Study Guide and ACMA is not responsible for the results obtained from the use of such information. Determination of the suitability of the information in the Study Guide other than for the preparation for the CCT Examination is the sole responsibility of the user. This Study Guide is sold without warranties, express or implied, including but not limited to any implied warranty of merchantability or fitness for a particular purpose. ACMA expressly disclaims all such warranties. ACMA is not responsible for any damage or loss caused or alleged to be caused by the information contained herein. Accordingly, ACMA shall not be liable for any direct, indirect, incidental, special or consequential damages, resulting from the use of the Study Guide. ACMA does not accept any liability based on the designation conferred upon an individual who successfully completes the certification program. Any company recognizing the conference of such a designation is responsible for verifying any and all credentials and skills of anyone with the CCT designation American Composites Manufacturers Association 1010 North Glebe Road, Suite 450 Arlington, VA Phone: Fax: All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission from the publisher. Printed in the United States 2

5 Table of Contents Introduction Composites in Wind Energy Definition of Composites...5 Why Composites Are Used...5 Where Composites Are Used...6 Module 1 Composite Materials in Wind Energy Section 1: Overview...11 Section 2: Polymers...11 Section 3: Reinforcements...17 Section 4: Cores...20 Section 5: Adhesives...21 Section 6: Surface Coatings...22 Section 7: Fillers Module 2 Composite Fabrication in Wind Energy Section 1: Overview...29 Section 2: Fabrication Processes for Wind Energy Applications...29 Section 3: Secondary Fabrication...34 Module 3 Composite Component Repair Section 1: Background...39 Section 2: Identifying the Composite...40 Section 3: Damage and Defect Inspection...41 Section 4: Damage Removal...42 Section 5: Repair...44 Section 6: Vacuum Infusion...49 Section 7: Repair to the Lightning Protection System American Composites Manufacturers Association 3

6 Table of Contents Certified Composites Technician Wind Blade Repair Study Guide Module 4 Wind Energy and Composites Safety Section 1: Introduction...57 Section 2: Chemicals, Handling and Storage...58 Section 3: Confined Space...62 Section 4: Electricity...63 Section 5: Climbing...65 Section 6: On-Site Safety...66 Module 5 Wind Energy and Composites Quality Assurance Section 1: Introduction...71 Section 2: A Quality System Model...71 Section 3: Quality Assurance Composite Repair...72 Appendix I Glossary...77 Appendix II Conversion Charts Appendix III A Typical Field Work Instruction Outline Appendix IV Sample Resin Mix Tables Appendix V Sample Laminate Schedule Appendix VI Sample Quality Inspection Record Appendix VII Sample Temperature Record Appendix VIII Wind Turbine Blade Cross-section Appendix IX Wind Turbine Diagram

7 Certified Composites Technician Wind Blade Repair Study Guide Introduction Introduction to Composites in Wind Energy Definition of Composites The definition of a composite two or more dissimilar materials which when combined are stronger than the individual materials is a good general definition but is much too broad for the purposes of our composites industry. This definition includes a wide range of material combinations, such as wood, adobe bricks, steel and concrete, rubber and steel (tires), concrete, and the combination of polymer resins and fibers. The intermediate definition the combination of a reinforcement material in a matrix or binder material is more focused for our specific composites industry as it narrows the range of materials to reinforcement and a matrix. However, in this case, reinforcements could include fibers or particles, and the matrix could be a polymer resin, a ceramic, or even a metal. Examples include: metal and ceramic matrix materials, reinforced thermoplastics, and reinforced thermoset polymer resins. The precise definition of thermoset composites as an engineering material appropriate for advanced composites and the wind energy markets is based on the physical properties of these materials. The combined action created by the load transfer between fibers and the chemical bonding of the reinforcement to the matrix, are the defining terms of this description. For the purposes of this program, composites are a combination of a reinforcement fiber in a thermoset polymer resin matrix, where the reinforcement has an aspect ratio that enables the transfer of loads between fibers, and the fibers are chemically bonded to the resin matrix. Why Composites Are Used When compared to other materials, composites can be designed to provide light weight and high strength. Composites are used to produce structures with the highest strength-to-weight ratios known to man. By utilizing a combination of resins and reinforcements, composite materials can be designed to meet the strength requirements of an application. This ability to custom tailor a composite to meet the mechanical and physical properties of a structure is a distinct advantage of composites over other materials. The resulting designed composites exhibit higher specific strength than other material options (for example, steel and aluminum). Specific strength is a term that relates strength-to-weight ratios. Composites have a higher specific strength than many other materials. In comparing the tensile and compressive strength of a.25" diameter steel rod and 2011 American Composites Manufacturers Association 5

8 Introduction Certified Composites Technician Wind Blade Repair Study Guide a.25" diameter fiberglass composite rod the steel rod will have higher tensile and compressive strength, but it will weigh more. If the fiberglass rod were increased in diameter so that it weighed the same as the steel rod, it would be stronger. Thus, from this example, per unit of weight, the composite rod is stronger than the steel rod. Composites can also be designed and produced to yield far superior corrosion resistance. Composite products provide long-term resistance to severe chemical and extreme temperature environments. Composites are often the material of choice for outdoor exposure, chemical handling applications and severe environment service. Composites also offer an advantage over other materials because of their ability to form shapes. Composites can be formed into complex and accurate shapes easier than other materials. This gives designers the freedom to create any shape or configuration. Furthermore, they can be molded into complex shapes at relatively low cost. The flexibility of creating complex shapes offers designers a freedom that is a hallmark of composites achievement. Composite structures are inherently durable. The longevity of composites, along with their low maintenance requirements, is a major benefit in critical applications. There are examples of composites boats, buildings and other structures built in the 1950s that have now been in service for over fifty years. There are also impressive case histories of fiberglass ductwork and underground storage tanks being in service in chemical manufacturing plants for over 25 years operating in harsh chemical environments 24 hours a day, seven days a week. How long do composites last? The answer is we do not know. We have not come to the end of the life of many original composites applications. Fiberglass reinforced dowel rods were manufactured and put into a highway application in Ohio in the 1960s. These rods were removed from the highway in the year 2000 and upon inspection showed no corrosion or deterioration. Later testing revealed that these bars retained their original tensile and compressive strengths. Where Composites Are Used The ability of composite materials to produce a high-quality, durable, costeffective product has long been known by manufacturers, designers and engineers. Today, as the drive for higher performance and lower cost materials continues, composite materials are readily found in many of the products used in our day-to-day lives. In addition to current applications in the cars we drive to the boats, RVs, skis, and golf clubs we use, composites are also being used in many 6

9 Certified Composites Technician Wind Blade Repair Study Guide Introduction critical industrial, aerospace, and military applications. In a marketplace where demands for product performance are ever increasing, composite materials have proven to be effective in reducing costs and improving performance. Composites solve problems, raise performance levels, and enable the development of many new products. Wind blades are turbine-mounted air foils. In use, they behave like highly engineered wings. Subject to the same complex forces that an aircraft wing is, best practices in design and manufacture are required when building wind blades to ensure their efficiency and functionality. The requirements for improved performance combined with the need for larger, stronger blades makes composites a perfect fit. Composite materials are stronger, lighter and can withstand fatigue. Composites dominate the wind turbine market because of their superior fatigue characteristics, superior strength-to-weight ratios, and their inherent ability to incorporate complex geometric shapes in their design. Today, most wind turbine towers are about 265 ft (80 m) in height and are fabricated from steel. Towers must be strong enough to support the weight of the turbine (approximately 100 tons) and also have the strength to resist buckling under the stress of the rotating turbine blades. Steel poles are fabricated in sections, some as large as 14 feet in diameter by 70 feet long, and trucked individually to the job sites. As the wind energy industry looks for more efficiency in producing electricity from wind, improved blade design will require longer blades. Longer blades will require higher towers. Towers that will reach over 100 m (328 feet) will allow these larger blades to access greater wind speeds, improving operating performance, and lowering operating costs. These towers will be made from composites, possibly manufactured on-site similarly to the Fiber-Reinforced Plastic (FRP) stack liners now used by the major power generation plants. The drive for lighter weight, stronger and stiffer components make composites the likely choice of materials to use in the wind energy industry. Besides turbine blades, the manufacture of nacelles, nose cones (or spinners) and housings also take advantage of composites. The global wind energy market has grown approximately 20% annually since the year It is estimated that composites supplying this growing market will exceed $6 billion by the year American Composites Manufacturers Association 7

10 Introduction Certified Composites Technician Wind Blade Repair Study Guide Introduction Questions 1. What is the definition of a composite as used in the wind energy industry? 2. When compared to other materials, composites can be designed to provide light weight and high strength. Explain how this is an advantage in wind energy. 3. What is specific strength as it relates to composites? Explain. 4. How long do composites last? Explain. 8