Essentials of Advanced Composite Fabrication & Repair

Louis C. Dorworth, Ginger L. Gardiner, Dr. Greg M. Mellema

• Editore: Aviation Supplies & Academics, Inc.
• Anno: 2019
• ISBN:
  9781619547636
• Argomento: Technology & Engineering
• Categoria: Materials Science

Advanced composite technology is constantly changing and embracing new developments daily, yet most of the basics needed to successfully design, fabricate and repair composite structures remain the same. Essentials of Advanced Composite Fabrication & Repair works as the perfect introductory textbook for beginners yet is also functional for the composite professional. It teaches the concepts and methods in a simple and straightforward way for a wide array of composite fundamentals, including fiber and matrix selection, molding methods, curing and achieving desired properties, tooling, testing and non-destructive inspection, step-by-step repair instructions and troubleshooting, key environmental, health and safety issues, and much more. New for this Second Edition are an introduction to nanomaterials in composites, and improved molding methods, adhesive bonding, joining and fastening coverage. Also updated with the advances in matrix technology and fiber reinforcements, as well as tooling, filament winding and various testing and inspection method improvements. Based on the authors' combined 90 years in the industry, this textbook is also a compendium of industry information, presented with full-color illustrations and photography. Fabric styles, core types, design guides, and detailed product information in the industry, and more, makes this book essential to anyone working in composites — from material and process engineers, to repair technicians and maintenance mechanics. Including bibliographic information, a glossary and index, it also serves as the companion textbook to most Abaris Training basic courses.

Chapter 1:

Composite Technology Overview

Composites vs. Advanced Composites

Composites are comprised of two or more materials working together, where each constituent material retains its unique identity within the composite and contributes its own structural properties, yet upon combination the resulting material has superior properties to those of its constituents. A good example of an everyday composite material is concrete. Concrete is made with select amounts of sand, aggregate, and perhaps even glass fiber mixed with cement to bind it together. If the concrete were broken open, the individual constituents would be visible. The type and quantities of these individual constituents can also be adjusted to give the resulting concrete different properties depending on the application.

This textbook is focused on composite laminates, which combine fibers and a matrix material that binds the fibers together. There are many different types of composite materials in use today. One example is fiber-reinforced plastic (FRP) composites made with short glass fibers in a polymer resin or plastic matrix. These materials are used in bath tubs, showers, pools, doors, car fenders, and a variety of construction materials including wall panels, corrugated sheet, profiles, and skylights. (Figure 1-1)

Figure 1-1. Fiber-reinforced composite

Highly loaded composite structures typically use continuous or long-fiber reinforcement that transfers load along bundles or layers (plies) of fibers arranged to run the length and width of the structure, much like the layers in a sheet of plywood. This type of composite laminate is used in the manufacture of boats, bridges, snowboards, bicycle frames, race cars, aircraft and spacecraft structures, to mention a few.

❱ Advanced Composites

“Advanced composites” are generally considered to be those that use advanced reinforcements such as carbon, aramid and S2 glass fibers that exhibit high strength-to-weight ratios.¹ They are typically more expensive, with more precisely tailored properties to achieve a specific objective.

¹ASM Handbook Volume 21, Composites (pg. 1113) defines “advanced composites” as: “Composite materials that are reinforced with continuous fibers having a modulus higher than that of fiberglass fibers. The term includes metal matrix and ceramic matrix composites, as well as carbon-carbon composites.” Material Park, Ohio; ASM International, 2001.

Fiberglass vs. Advanced Composites

Some composites are generally referred to as “fiberglass” due to their use of randomly-oriented, chopped glass fiber (E-glass) and polyester resin, whereas most aerospace structural parts are made using precisely-laid plies of carbon fiber/epoxy prepreg, an example of advanced composites. (Figure 1-2)

Figure 1-2. Fiberglass vs. advanced composites
[a] To fabricate an aerospace structural component, technicians carefully lay down each ply of carbon-fiber prepreg prior to vacuum bagging and autoclave cure. Green “templates of light” are accurately projected from a 3D laser projector to ensure precise positioning of the ply. (Photo courtesy of Assembly Guidance)
[b] Chopped fiberglass and resin are sprayed onto a gel-coated mold to form the outer shell of a Class 8 truck hood. However, this is a more advanced and higher performance example of spray-up fiberglass because the shell is cured in an oven at 130°F and then reinforced with structural members made using RTM, which are secondarily bonded in-place using methacrylate adhesive. (Photo courtesy of Marine Plastics Ltd.)

Examples of Typical Applications

Large components of commercial airliners — such as the vertical and horizontal tail plane (stabilizer) on the Airbus A320, A330/340, A380 and Boeing 777, the wing, center wing b...