Aerospace carbon-fiber composites

Composites. Various composite materials have evolved over the years as a significant class of high performance textile products. The prototype composite is carbon fiber with an epoxy resin matrix for stmctural akcraft components and other aerospace and military appHcations. Carbon fiber composites ate also used in various leisure and spotting items such as golf clubs, tennis rackets, and lightweight bicycle frames. However, other types of appHcations and composites ate also entering the marketplace. For example, short ceUulose fiber/mbbet composites ate used for hoses, belting, and pneumatic tire components. 

Graphite Carbon Manufacturing Aerospace Industrial Composites Fuel Cell Components Carbon Fibers Composite Materials Fine-Grain Graphites Wind Turbine Blades... 

An up-date of the status of EB curing of carbon fiber composites was presented by A. Berejka. Developments proven successful for aerospace applications are now being seriously scrutinized for automotive use. The diversity of proven uses of radiation grafting for uses in batteries, porous film and non-woven filters, and release coated films and papers was also presented. Opportunities for use of grafting in biomedical applications, composites technology, and fuel cell membrane development were also discussed. 

As described by DuPont researchers, significant weight saving and low flammability are the primary driving forces behind the adoption of Kevlar by the aircraft industry. Kevlar-epoxy composites are 25-50% lighter than those from glass and aluminum and have better tensile properties. Because thermotropic LCPs offer a low viscosity for the impregnation of carbon fibers and excellent chemical resistance, LCP-carbon fiber composite has been developed as a secondary composite for the aerospace industry [6]. 

While the overall growth of composites in the aerospace industry is continuing, epoxy has been facing stiff competition from other materials and the growth rate has been relatively small (2% annually). While epoxies are still used in many exterior aircraft parts, carbon fiber composites based on bismaleimide and cyanate esters have shown better temperature and moisture resistance than epoxies in military aircaft applications. In the commercial aircraft arena, phenolic composites are now preferred for interior applications because of their lower heat release and smoke generation properties during fires. High performance thermoplastics, such as polysulfone, polyimides, and polyetherether ketone (PEEK), have also foimd some uses in aerospace composites. 

A Figure 22.45 Carbon composites are used extensively in aerospace and automotive applications, and in sporting goods. This high-performance (and high-priced ) off-road bike has a carbon-fiber-composite frame, which makes it very lightweight and helps it absorb road shocks. 

Carbon-fiber composites are found in many new structural applications such as racing cars, fishing poles, tennis rackets, competition skis, and sailboat spars. However, their greatest impact is in the aerospace industry with applications in the space shuttle, advanced passenger airplanes, aircraft brakes, and many others. 

The extensive use of carbon fiber composites in aerospace is illustrated in Fig. 9.1. This figure shows the large number of applications of polymer/carbon-fiber composites in a new passenger plane, the McDonnell-Douglas Aircraft MD-12X. Other new airplanes, such as the Boeing 777 and the Airbus A340, make similar extensive use of these composites. ] The Airbus A340, for instance, incorporates 4000 kg of epoxy-carbon fiber... 

The introduction of carbon-fiber composites has been slower in other areas such as the automotive industry where cost is a major factor and weight is not as critical as it is in aerospace applications. 

The most common matrix materials of carbon-fiber composites are the polymers, also called resins or plastics. Carbon-reinforced polymers are low-density, high-strength, and high-modulus composites with extensive applications, especially in aerospace as mentioned above. Their cost is still high but is gradually decreasing as the fabrication techniques are becoming less labor-intensive. 

The use of nanocomposites to reinforce traditional composites has also been increasing and will continue to be a near-term trend. The emphasis for these applications, however, has been on additional mechanical reinforcement rather than flammability reduction.Since more traditional fiber-filled composites are exposed to fire risk scenarios, it makes sense to use a nanocomposite with the traditional composite to improve both mechanical and flammability performance. Of course, this does create an additional level of complexity, especially in handling the large increases in viscosity seen with nanocomposites used with thermoset composites. At this time, most nanocomposite-fiberglass/carbon fiber composites are used for military and aerospace applications, but the benefit of lightweight materials may also move these materials into automotive and mass transportation (e.g., bus, rail), where flammability performance is strongly needed. 

Automotive applications include body panels, belts, tires, hoses, composite drive shafts. One of the authors knows local race car drivers in Denver, who will thermoform plastic door panels for their race cars with an ordinary shop vacuum. Recently, there has been a carbon fiber composite automobile frame proposed by Colorado Company. Aerospace applications are airplane wings, filament-wound rocket bodies. There are also homebuilt experimental aircraft which are rolled into the sun to cure the epoxy matrix. One of the largest composite structures in space is the composite arm made by Canada for the Space Station. 

Aerospace struetwes made of composite. As part of the evaluation of the developed ultrasonic spectroscopy system the NSC software was tested on ultrasonic resonance spectra from composite panel samples. Spectra were collected with four different types of damages, and from flawless samples. The damages included a small cut in one of the carbon fiber... 

Carbon, Carbides, and Nitrides. Carbon (graphite) is a good thermal and electrical conductor. It is not easily wetted by chemical action, which is an important consideration for corrosion resistance. As an important stmctural material at high temperature, pyrolytic graphite has shown a strength of 280 MPa (40,600 psi). It tends to oxidize at high temperatures, but can be used up to 2760°C for short periods in neutral or reducing conditions. The use of new composite materials made of carbon fibers is expected, especially in the field of aerospace stmcture. When heated under... 

Today, carbon fibers are still mainly of interest as reinforcement in composite materials [7] where high strength and stiffness, combined with low weight, are required. For example, the world-wide consumption of carbon fibers in 1993 was 7,300 t (compared with a production capacity of 13,000 t) of which 36 % was used in aerospace applications, 43 % in sports materials, with the remaining 21 % being used in other industries. This consumption appears to have increased rapidly (at 15 % per year since the early 1980s), at about the same rate as production, accompanied by a marked decrease in fiber cost (especially for high modulus fibers). 

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