Carbon fiber reinforced polymer

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Polymer reinforced carbon fiber , reinforced plastic carbon fiber or reinforced thermoplastic carbon fiber ( CFRP , CRP , CFRTP or often just carbon fiber , carbon composite or even carbon ), is very strong and light fiber-reinforced plastic containing carbon fiber. Common alternative spelling 'fiber' in Commonwealth countries. CFRPs can be expensive to produce but are typically used wherever a high strength-to-weight ratio and rigidity are required, such as aerospace, automotive, civil engineering, sporting goods and an increasing number of other consumer and technical applications.

Binding polymers are often thermoset resins such as epoxy, but other thermoset or thermoplastic polymers, such as polyester, vinyl ester or nylon, are sometimes used. Composites may contain aramid (eg Kevlar, Twaron), aluminum, ultra-heavy molecular weight polyethylene (UHMWPE) or glass fibers other than carbon fibers. The properties of the final CFRP product can also be affected by the additive type introduced into the resin matrix. The most common additive is silica, but other additives such as rubber and carbon nanotubes can be used. This material is also referred to as graphite-reinforced polymers or the fiber-reinforced polymer graphite ( GFRP less commonly, due to clash with glass- home polymer).

Video Carbon fiber reinforced polymer

Properti

CFRP is a composite material. In this case the composite consists of two parts: matrix and reinforcement. In CFRP, the amplifier is carbon fiber, which gives strength. Matrices are usually polymer resins, such as epoxy, to bind reinforcements together. Because CFRP consists of two distinct elements, the material properties depend on these two elements.

Strengthening will give CFRP its strength and rigidity; measured by the voltage and elastic modulus respectively. Unlike isotropic materials such as steel and aluminum, CFRP has the nature of directional strength. The properties of CFRP depend on the layout of the carbon fiber and the proportion of the carbon fiber relative to the polymer. Two different equations governing the modulus of clean elasticity of composite materials using properties of carbon fibers and polymer matrices can also be applied to carbon fiber reinforced plastics. The following equation,

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The fracture toughness of carbon fiber reinforced plastic is governed by the following mechanisms: 1) debonding between carbon fiber and polymer matrix, 2) tensile fiber, and 3) delamination between CFRP sheets. Typical epoxy CFRP shows virtually no plasticity, with less than 0.5% strain on failure. Although CFRP with epoxy has a high strength and elastic modulus, fragile fracture mechanics presents a unique challenge for engineers in the detection of failure because failure occurs gratuitously. Thus, recent efforts to strengthen CFRP include modifying existing epoxy materials and finding alternative polymer matrices. One material with high promise is PEEK, which shows an order of magnitude greater toughness with the same modulus of elasticity and tensile strength. However, PEEK is much more difficult to process and more expensive.

Despite the high initial strength-to-weight ratio, the limitations of CFRP designs are the lack of defined tired resistance limits. This means, theoretically, that the failure of the stress cycle can not be ruled out. While steel and many other structural and alloy metals have an estimated tired durability limit, complex composite failure modes mean that the CFRP fatigue failure traits are difficult to predict and are designed for. Consequently, when using CFRP for important cyclic loading applications, engineers may need to design within a sufficiently large security strength limit to provide reliable component reliability throughout their service life.

Environmental effects such as temperature and humidity can have a profound effect on polymer-based composites, including most CFRPs. While CFRPs exhibit excellent corrosion resistance, the effects of moisture over a wide temperature range can lead to degradation of mechanical properties of CFRPs, particularly in fiber-matrix interfaces. While the carbon fiber itself is not affected by the moisture spread into the material, moisture coats the polymer matrix. The epoxy matrix used for engine fan blades is designed to withstand jet fuel, lubrication, and rainwater, and external paints on composite parts are applied to minimize damage from ultraviolet light.

Carbon fibers can cause galvanic corrosion when CRP parts are attached to aluminum.

Maps Carbon fiber reinforced polymer

Producing

The main elements of CFRP are carbon filaments; these are produced from precursor polymers such as polyacrylonitrile (PAN), rayon, or petroleum pitch. For synthetic polymers such as PAN or rayon, the precursor is first spun into filament yarn, using chemical and mechanical processes to align the polymer chain by increasing the final physical properties of the complete carbon fiber. The compositions of the precursors and the mechanical processes used during spinning filament yarns may vary between manufacturers. After drawing or spinning, the polymer filament yarn is then heated to drive a non-carbon atom (carbonization), producing the final carbon fiber. The carbon fiber filament yarn can be further processed to improve the handling quality, then rolled into a coil. Of these fibers, a unidirectional sheet is made. These sheets are layered to each other in a quasi-isotropic layup, eg. 0 Â °, 60 Â ° or -60 Â ° relative to each other.

From basic fibers, two-way woven sheets can be made, ie twill with woven 2/2. The process by which most CFRPs are made varies depending on the part made, the finishing (outside gloss) required, and how many of these special parts will be produced. In addition, the choice of matrix can have a profound effect on the properties of the finished composite.

Many parts of CFRP are made with a layer of carbon cloth supported with fiberglass. A device called a chopper gun is used to make this composite part quickly. After a thin shell is made of carbon fiber, the chopper gun cuts the fiberglass rolls into short lengths and sprays the resin at the same time, so that the fiberglass and resin are mixed in place. The resin is an external mixture, in which the resiners and resins are sprayed separately, or internal mixtures, which require cleaning after each use. The manufacturing method may include the following:

Molding

One method of producing CFRP parts is by coating the carbon fiber fabric sheets into the mold in the final product form. The alignment and accumulation of fabric fibers is selected to optimize the strength and stiffness properties of the resulting material. The mold is then filled with epoxy and heated or cured with air. The resulting part is highly corrosion-resistant, rigid, and robust for its weight. Parts used in less critical areas are produced by draining the cloth over the mold, with epoxy either prescribed into the fiber (also known as pre-preg or "painted" on it). High-performance parts using single molds are often bagged with vacuum and/or autoclave-healed, because even small air bubbles in the material will reduce strength. The alternative to the autoclave method is to use internal pressure through blowing of air bladder or EPS foam in non-dried carbon fibers.

Vacuum packing

For simple pieces that require relatively few copies (1-2 per day), a vacuum bag can be used. A fiberglass, carbon fiber or aluminum mold is polished and waxed, and has a removable material applied before the fabric and resin are applied, and the vacuum is pulled and set aside to allow the piece to heal (harden). There are three ways to apply the resin to the fabric in a vacuum mold.

The first method is manual and is called a wet layup, in which the two-part resin is mixed and applied before being placed in the mold and placed in the bag. The other is done by a drip, where a dry cloth and a mold is placed inside the bag while the vacuum pulls the resin through a small tube into the bag, then through a tube with a hole or something similar to evenly spread the resin throughout the fabric. Wire loom works perfectly for tubes that require holes in the bag. Both methods of application of this resin require handwork to spread the resin evenly to a glossy finish with very small pin holes.

The third method of building a composite material is known as a dry layup. Here, the carbon fiber material has been impregnated with resin (pre-preg) and applied to the mold in a manner similar to film adhesive. This assembly is then placed in a vacuum to be healed. The dry layup method has the least amount of waste resin and can achieve a lighter construction than the wet layup. Also, since larger amounts of resins are more difficult to remove by wet layup methods, pre-preg parts generally have fewer small holes. Pinhole removal with minimal amount of resin generally requires the use of autoclave pressure to clean up the rest of the gas.

Compression printing

A faster method uses a compression mold. It is a two-piece mold (male and female) which is usually made of aluminum or steel pressed together with a cloth and resin in between. The benefit is the overall speed of the process. Some car manufacturers, such as BMW, are claimed to be able to rotate the new part every 80 seconds. However, this technique has a very high initial cost because the mold requires CNC machining with very high precision.

Filament rolls

For difficult or convoluted shapes, the filament retainer may be used to create a CFRP part by rotating the filament around the mandrel or core.

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Apps

Applications for CFRP include the following:

Aerospace Engineering

Airbus A350 XWB built from 52% CFRP including wing wing and plane components, overtaking Boeing 787 Dreamliner, for aircraft with the highest weight ratio for CFRP, held at 50%. This is one of the first commercial aircraft to have wing spouts made of composites. The Airbus A380 was one of the first commercial aircraft to have a central wing-box made of CFRP; this is the first to have a smooth contoured cross section of wings, not the wings that are split into sections. This continuous flowing stream optimizes aerodynamic efficiency. In addition, the trailing edge, together with the rear screen, the empennage and un-pressurized fuselage are made of CFRP. However, many delays have pushed the order delivery date back due to problems with the creation of these sections. Many aircraft using CFRP have experienced delays with delivery dates because relatively new processes are used to make CFRP components, whereas metal structures have been studied and used on airframes for years, and the process is relatively well understood. The recurrent problem is the monitoring of structural aging, where new methods are constantly being investigated, due to the unusual nature of the multi-material and anisotropic CFRP.

In 1968 a series of carbon fiber fans Hyfil were operating in Rolls-Royce Conways of Vickers VC10s operated by BOAC.

The designer and manufacturer of specialist aircraft, Scaled Composites have used CFRP extensively throughout their design range, including the first manned spacecraft to be wed by Spaceship One. CFRP is widely used in micro air vehicles (MAVs) because of their high strength and weight ratio.

SpaceX uses carbon fiber for the entire main structure of their new heavy-lift launch vehicle, the ITS launch vehicle - as well as two very large spacecraft to be launched by it, the inter-planetary transport and tanker ITS . This is a particular problem for large liquid oxygen tank structures due to design challenges such as solid carbon/oxygen contact for long periods of time.

Automotive engineering

CFRPs are widely used in high-end car racing. The high cost of carbon fiber is reduced by the unequaled strength-to-weight ratio of the material, and the low weight is essential for high-performance car racing. The racing car manufacturer has also developed a method to deliver the carbon fiber pieces of force in a certain direction, making it strong in load-bearing directions, but weak in directions where little or no load will be placed on the members. Instead, manufacturers develop omnidirectional carbon fiber weaving that applies strength in all directions. This series of carbon fibers is most widely used in the "safety cell" monocoque frame assemblies of high-performance racing cars.

Many supercars over the last few decades have included CFRP extensively in its manufacture, using it for their monocoque chassis as well as other components. As far back as 1971, CitroÃÆ'¡n SM offers optional lightweight carbon fiber wheels.

The use of this material is more easily adopted by low-volume manufacturers who use it primarily to create body panels for some of their high-end cars due to their increased strength and decreasing weight compared to glass-reinforced polymers used for the majority of their products.

Civil engineering

CFRP has become an important material in structural engineering applications. Learning in the academic context of its potential benefits in construction, it also proves itself cost-effective in a number of field applications that strengthen concrete, masonry, steel, cast iron, and wooden structures. Its industrial use may be retrofitting to strengthen existing structures or as an alternative (or pre-suppressing) reinforcement material rather than steel from the beginning of the project.

Retrofit has become an increasingly dominant use of materials in civil engineering, and applications include increasing the load capacity of old structures (such as bridges) designed to tolerate service loads much lower than they currently are, seismic retrofit, and repair of damaged structures. Retrofitting is very popular in many instances because the cost of replacing the less than perfect structure can greatly exceed the cost of reinforcement using CFRP.

Applicable to reinforced concrete structures for bending, CFRP typically has a major impact on strength (doubling or over the strength of this section is not uncommon), but only a moderate increase in stiffness (possibly a 10% increase). This is because the material used in these applications is usually very strong (eg, 3000 MPa main tensile strength, more than 10 times the mild steel) but not too stiff (150 to 250 GPa, slightly less than steel, is typical). As a result, only a small cross-section of material is used. Small areas with very high strength but moderate stiffness materials will significantly increase strength, but not stiffness.

CFRP can also be applied to increase the shear strength of reinforced concrete by wrapping a cloth or fiber around the part to be reinforced. Wrapping parts (such as bridges or building columns) can also increase the ductility of parts, greatly increasing the resistance to collapse under the earthquake load. Such 'seismic retrofits' are the main applications in earthquake prone areas, because they are much more economical than alternative methods.

If the circular column (or nearly so) the axial capacity increase is also achieved by wrapping. In this application, CFRP wrapping cages increase the compressive strength of concrete. However, although large increases are achieved at the highest congestion load, the concrete will crack with only a slight increase in load, which means that the application is only occasionally used. CFRP modulus of ultra-high specialist (with a pull modulus of 420 GPa or more) is one of several practical methods for strengthening cast iron. In typical usage, it is tied to the tensile flanges of the part, either increasing the stiffness of the part and lowering the neutral axis, thus greatly reducing the maximum tensile stress in the cast iron.

In the United States, pre-press concrete cylinder pipes (PCCP) are responsible for most water transmission lines. Because of its large diameter, PCCP failures are usually a major disaster and affect large populations. Approximately 19,000 miles (31,000 km) of PCCP was installed between 1940 and 2006. Corrosion in the form of hydrogen embrittlement has been blamed for the gradual deterioration of pre-compressed cable in many PCCP lines. Over the last decade, CFRP has been used to internally outline PCCP, resulting in a fully structural reinforcement system. Inside the PCCP line, CFRP liners act as a barrier that controls the level of tension experienced by steel cylinders in the host pipe. Composite liners allow steel cylinders to perform in elastic ranges, to ensure long-term performance of pipes maintained. The CFRP ship design is based on the strain compatibility between the liner and the host pipe.

CFRP is a more expensive material than its counterparts in the construction industry, glass fiber-reinforced polymer (GFRP) and aramid fiber-reinforced polymer (AFRP), although CFRP, in general, is considered to have superior properties. Much research continues to be made on the use of CFRP for both retrofitting and as an alternative to steel as a strengthening or pre-stressing material. Costs remain a problem and long term survival questions still exist. Some are concerned about the fragile nature of CFRP, in contrast to the ductility of the steel. Although design codes have been created by institutions such as the American Concrete Institute, there are still doubts among the technical community about applying these alternative materials. This is partly due to the lack of standardization and the nature of the combination of fibers and resins in the market.

Carbon fiber microelectrodes

Carbon fibers are used for the manufacture of carbon fiber microelectrodes. In this application is usually one carbon fiber with a diameter of 5-7? M sealed in capillary glass. At the end of the capillary it is sealed with epoxy and polished to make microelectric disc of carbon fiber or fiber cut to length 75-150? M to make carbon-fiber cylinder electrodes. Carbon fiber-micro fibers are used either in amperometry or fast-cycle cyclic voltammetry to detect biochemical signals.

Sporting goods

CFRP is now widely used in sports equipment such as in squash, tennis and badminton rackets, kite sports sparel, high quality arrow shoots, hockey sticks, fishing rods, surf boards, high end swimming fins, and paddle paddles. Amputation athletes like Jonnie Peacock using carbon fiber blades to run. It is used as a shank plate in some basketball shoes to keep the feet steady, usually running the length of the shoe just above the sole and left open in some areas, usually in the arch.

Controversially, in 2006, cricket bats with a thin layer of carbon fiber on the back were introduced and used in competitive matches by top players including Ricky Ponting and Michael Hussey. Carbon fiber is claimed only to improve bat's endurance but is banned from all first class matches by ICC in 2007.

CFRP bicycle frames weigh less than one steel, aluminum, or titanium for the same strength. The type and orientation of the woven carbon fiber can be designed to maximize the stiffness in the required direction. Frames can be set to tackle different driving styles: sprint events require more rigid frames while endurance events may require more flexible frames for driver comfort in longer periods. The various forms that can be built further enhance the stiffness and also allow the aerodynamic tube parts. CFRP forks including suspension and steering forks, handlebars, seatposts, and crank arms are becoming more common on medium bikes and higher prices. The CFRP rim remains expensive but its stability compared to aluminum reduces the need to revive the wheel and reduce the mass of reduced torque inertial moments. The fingers of CFRP are rare and most of the carbon wheel retains the traditional stainless steel radius. CFRP also appears more and more in other components such as derailleur parts, brake levers and shifter and body, tape sprocket carriers, suspension joints, disc brake rotors, pedals, shoe soles, and saddle rails. Although strong and lightweight, impact, over-torquing or incorrect installation of CFRP components has resulted in cracks and failures, which may be difficult or impossible to repair.

Other apps

The fire resistance of polymers and thermo-composite composites is significantly increased if a thin layer of carbon fiber is formed near the surface because the densely packed carbon fiber layer efficiently reflects heat.

CFRP also finds applications in increasing the number of high-end products that require stiffness and low weight, these include:

• Musical instruments, including violin bow, guitar pick and pick-guard, drum shell, bagpipe chanter and all instruments such as Luis and Clark's cellos carbon fiber, violin and violin; and acoustic guitars Blackbird Guitars and ukuleles, as well as audio components such as turntables and loudspeakers.
• Firearms use it to replace certain metal, wood, and fiberglass components, but many internal parts are still limited to metal alloys because the reinforced plastics are not currently compatible.
• High-performance drone boards and other radio controlled vehicle and aircraft components such as helicopter rotor blades.
• Light poles such as: tripod feet, tent poles, fishing rods, billiard cues, walking sticks and high-end poles like to clean windows.
• Dentistry, carbon fiber posts are used to restore root canal dental treatment.
• Railed carriage bogies for passenger service. This reduces weight by up to 50% compared to metal bogies, which contributes to energy savings.
• Laptop shells and other high performance cases.
• Carbon woven fabrics.

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Disposal and recycling

CFRP has a long service life when protected from the sun. When it's time to disable CFRP, they can not be melted in the air like a lot of metal. When free of vinyl (PVC or polyvinyl chloride) and other halogenated polymers, CFRP can be thermally decomposed through thermal depolymerization in an oxygen-free environment. This can be achieved in the refinery in a one-step process. Capture and reuse of carbon and monomers is then possible. CFRP can also be milled or shredded at low temperatures to regain carbon fiber; However, this process shortens the fiber dramatically. Just as with recycled paper, the shortened fibers cause the recycled material to be weaker than the original material. There are still many industrial applications that do not require full length carbon fiber reinforcement. For example, carbon fiber chopped reclamation can be used in consumer electronics, such as laptops. This provides excellent reinforcement of the polymer used even if it does not have a strength-to-weight ratio of aerospace components.

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Polymer reinforced carbon nano-tube (CNRP)

In 2009, Zyvex Technologies introduced carbon nanotube-reinforced epoxy and carbon pre-pregs. Carbon nanotube reinforced polymer (CNRP) is several times stronger and tougher than CFRP and is used in Lockheed Martin F-35 Lightning II as a structural material for aircraft. CNRP still uses carbon fiber as the main amplifier, but the binding matrix is ​​an epoxy containing nanotube tubes.

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See also

• Carbon (fiber)
• Carbon nanotubes
• Composite repair
• Fiber-reinforced plastics
• Running Blades Mechanics

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References

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External links

• Japan Carbon Fiber Manufacturers Association (UK)
• Engineers design a composite buffer system for injured Hokie running back Cedric Humes
• New Steel Articles 1968 Flights on carbon fiber announcements
• Carbon Fibers - First Five Year A 1971 Flights article on carbon fiber in the aviation field

Source of the article : Wikipedia