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  • Composite material


    Composites are formed by combining materials together to form an overall structure with properties that differ from that of the individual components A black carbon fibre (used as a reinforcement component) compared to a human hair A composite material (also called a composition material or shortened to composite, which is the common name) is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure, differentiating composites from mixtures and solid solutions. The new material may be preferred for many reasons: common examples include materials which are stronger, lighter, or less expensive when compared to traditional materials. More recently, researchers have also begun to actively include sensing, actuation, computation and communication into composites, which are known as Robotic Materials.



    A component view of a GLARE3-3/2 hybrid sheet. There are three layers of aluminum alternating with two layers of glass fiber. In a GLARE3 grade, each glass fiber layer has two plies: one oriented at zero degrees, and the other oriented at ninety degrees.Glass laminate aluminum reinforced epoxy (GLARE) is a fiber metal laminate (FML) composed of several very thin layers of metal (usually aluminum) interspersed with layers of S-2 glass-fiber pre-preg, bonded together with a matrix such as epoxy. The uni-directional pre-preg layers may be aligned in different directions to suit predicted stress conditions. Though GLARE is a composite material, its material properties and fabrication are very similar to bulk aluminum metal sheets. It has far less in common with composite structures when it comes to design, manufacture, inspection, or maintenance. GLARE parts are constructed and repaired using mostly conventional metal working techniques. Its major advantages over conventional aluminum are: Better "damage tolerance" behavior, especially in impact and metal fatigue. Since the elastic strain is larger than other metal materials, it can consume more impact energy. It is dented more easily but has a higher penetration resistance. Better corrosion resistance. Better fire resistance. Lower specific weight.Furthermore, the material can be tailored during design and manufacture so that the number, type and alignment of layers can suit the local stresses and shapes throughout the aircraft. This allows the production of double-curved sections, complex integrated panels, or very large sheets. While a simple manufactured sheet of GLARE is three to ten times expensive than an equivalent sheet of aluminum, considerable production savings can be made using the aforementioned optimization. A structure built with GLARE is lighter and less complex than an equivalent metal structure, requires less inspection and maintenance, and has a longer lifetime-till failure. These characteristics can make GLARE cheaper, lighter, and safer to use in the long run.

  • Sandwich-structured composite


    Composite sandwich structure panel used for testing at NASA A sandwich-structured composite is a special class of composite materials that is fabricated by attaching two thin but stiff skins to a lightweight but thick core. The core material is normally low strength material, but its higher thickness provides the sandwich composite with high bending stiffness with overall low density. Open- and closed-cell-structured foams like polyethersulfone polyvinylchloride, polyurethane, polyethylene or polystyrene foams, balsa wood, syntactic foams, and honeycombs are commonly used core materials. Sometimes, the honeycomb structure is filled with other foams for added strength. Open- and closed-cell metal foam can also be used as core materials. Laminates of glass or carbon fiber-reinforced thermoplastics or mainly thermoset polymers (unsaturated polyesters, epoxies...) are widely used as skin materials. Sheet metal is also used as skin material in some cases. The core is bonded to the skins with an adhesive or with metal components by brazing together. Diagram of an assembled composite sandwich (A), and its constituent face sheets or skins (B) and honeycomb core (C) (alternately: foam core)

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