(See related pages)
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| Composite material | a materials system composed of a mixture or combination of two or more micro- or macroconstituents that differ in form and chemical composition and are essentially insoluble in each other. (See page(s) 659; Sec. 11.1) |
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| Fiber-reinforced plastics | composite materials consisting of a mixture of a matrix of a plastic material such as a polyester or epoxy strengthened by fibers of high strength such as glass, carbon, or aramid. The fibers provide the high strength and stiffness, and the plastic matrix bonds the fibers together and supports them. (See page(s) 659; Sec. 11.2) |
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| E-glass fibers | fibers made from E (electrical) glass, which is a borosilicate glass and which is the most commonly used glass for fibers for fiberglass-reinforced plastics. (See page(s) 659; Sec. 11.2) |
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| S-glass fibers | fibers made from S glass, which is a magnesia-alumina-silicate glass and which is used for fibers for fiberglass-reinforced plastics when extra-high-strength fibers are required. (See page(s) 660; Sec. 11.2) |
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| Roving | a collection of bundles of continuous fibers twisted or untwisted. (See page(s) 660; Sec. 11.2) |
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| Carbon fibers (for a composite material) | carbon fibers produced mainly from polyacrylonitrile (PAN) or pitch that are stretched to align the fibrillar network structure within each carbon fiber and which are heated to remove oxygen, nitrogen, and hydrogen from the starting or precursor fibers. (See page(s) 660; Sec. 11.2) |
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| Tow (of fibers) | a collection of numerous fibers in a straight-laid bundle, specified according to the number of fibers it contains-e.g., 6000 fibers/tow. (See page(s) 660; Sec. 11.2) |
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| Aramid fibers | fibers produced by chemical synthesis and used for fiber-reinforced plastics. Aramid fibers have an aromatic (benzene ring type) polyamide linear structure and are produced commercially by the Du Pont Co. under the trade name of Kevlar. (See page(s) 660; Sec. 11.2) |
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| Specific tensile strength | the tensile strength of a material divided by its density. (See page(s) 660; Sec. 11.2) |
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| Specific tensile modulus | the tensile modulus of a material divided by its density. (See page(s) 660; Sec. 11.2) |
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| Laminate | a product made by bonding sheets of a material together, usually with heat and pressure. (See page(s) 660; Sec. 11.3) |
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| Unidirectional laminate | a fiber-reinforced-plastic laminate produced by bonding together layers of fiber-reinforced sheets that all have continuous fibers in the same direction in the laminate. (See page(s) 660; Sec. 11.3) |
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| Multidirectional laminate | a fiber-reinforced-plastic laminate produced by bonding together layers of fiber-reinforced sheets with some of the directions of the continuous fibers of the sheets being at different angles. (See page(s) 660; Sec. 11.3) |
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| Laminate ply (lamina) | one layer of a multilayer laminate. (See page(s) 660; Sec. 11.3) |
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| Hand lay-up | the process of placing (and working) successive layers of reinforcing material in a mold by hand to produce a fiber-reinforced composite material. (See page(s) 660; Sec. 11.4) |
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| Spray lay-up | a process in which a spray gun is used to produce a fiber-reinforced product. In one type of spray-up process, chopped fibers are mixed with plastic resin and sprayed into a mold to form a composite material part. (See page(s) 660; Sec. 11.4) |
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| Vacuum bag molding | a process of molding a fiber-reinforced-plastic part in which sheets of transparent flexible material are placed over a laminated part that has not been cured. The sheets and the part are sealed, and a vacuum is then applied between the cover sheets and the laminated part so that entrapped air is mechanically worked out of the laminate. Then the vacuum-bagged part is cured. (See page(s) 660; Sec. 11.4) |
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| Prepreg | a ready-to-mold plastic resin-impregnated cloth or mat that may contain reinforcing fibers. The resin is partially cured to a "B" stage and is supplied to a fabricator who uses the material as the layers for a laminated product. After the layers are laid up to produce a final shape, the layers are bonded together, usually with heat and pressure, by the curing of the laminate. (See page(s) 660; Sec. 11.4) |
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| Filament winding | a process for producing fiber-reinforced plastics by winding continuous reinforcement previously impregnated with a plastic resin on a rotating mandrel. When a sufficient number of layers have been applied, the wound form is cured and the mandrel removed. (See page(s) 660; Sec. 11.4) |
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| Sheet-molding compound (SMC) | a compound of plastic resin, filler, and reinforcing fiber used to make fiber-reinforced-plastic composite materials. SMC is usually made with about 25 to 30 percent fibers about 1 in. (2.54 cm) long, of which fiberglass is the most commonly used fiber. SMC material is usually pre-aged to a state so that it can support itself and then cut to size and placed in a compression mold. Upon hot pressing, the SMC cures to produce a rigid part. (See page(s) 661; Sec. 11.5) |
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| Pultrusion | a process for producing a fiber-reinforced-plastic part of constant cross section continuously. The pultruded part is made by drawing a collection of resin-dipped fibers through a heated die. (See page(s) 661; Sec. 11.5) |
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| Concrete (portland cement type) | a mixture of portland cement, fine aggregate, coarse aggregate, and water. (See page(s) 661; Sec. 11.6) |
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| Portland cement | a cement consisting predominantly of calcium silicates that react with water to form a hard mass. (See page(s) 661; Sec. 11.6) |
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| Aggregate | inert material mixed with portland cement and water to produce concrete. Larger particles are called coarse aggregate (e.g., gravel), and smaller particles are called fine aggregate (e.g., sand). (See page(s) 661; Sec. 11.6) |
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| Hydration reaction | reaction of water with another compound. The reaction of water with portland cement is a hydration reaction. (See page(s) 661; Sec. 11.6) |
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| Air-entrained concrete | concrete in which there exists a uniform dispersion of small air bubbles. About 90 percent of the air bubbles are 100 μm or less. (See page(s) 661; Sec. 11.6) |
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| Reinforced concrete | concrete containing steel wires or bars to resist tensile forces. (See page(s) 661; Sec. 11.6) |
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| Prestressed concrete | reinforced concrete in which internal compressive stresses have been introduced to counteract tensile stresses resulting from severe loads. (See page(s) 661; Sec. 11.6) |
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| Pretensioned (prestressed) concrete | prestressed concrete in which the concrete is poured over pretensioned steel wires or rods. (See page(s) 661; Sec. 11.6) |
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| Asphalt | a bitumen consisting mainly of hydrocarbons having a wide range of molecular weights. Most asphalt is obtained from petroleum refining. (See page(s) 661; Sec. 11.7) |
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| Asphalt mixes | mixtures of asphalt and aggregate that are used mainly for road paving. (See page(s) 661; Sec. 11.7) |
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| Wood | a natural composite material consisting mainly of a complex array of cellulose fibers in a polymeric material matrix made up primarily of lignin. (See page(s) 661; Sec. 11.8) |
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| Lignin | a very complex cross-linked three-dimensional polymeric material formed from phenolic units. (See page(s) 661; Sec. 11.8) |
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| Sapwood | the outer part of the tree stem of a living tree that contains some living cells that store food for the tree. (See page(s) 661; Sec. 11.8) |
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| Heartwood | the innermost part of the tree stem that in the living tree contains only dead cells. (See page(s) 661; Sec. 11.8) |
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| Cambium | the tissue that is located between the wood and bark and is capable of repeated cell division. (See page(s) 661; Sec. 11.8) |
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| Softwood trees | trees that have exposed seeds and arrow leaves (needles). Examples are pine, fir, and spruce. (See page(s) 661; Sec. 11.8) |
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| Hardwood trees | trees that have covered seeds and broad leaves. Examples are oak, maple, and ash. (See page(s) 661; Sec. 11.8) |
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| Parenchyma | food-storing cells of trees that are short with relatively thin walls. (See page(s) 662; Sec. 11.8) |
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| Wood ray | a ribbonlike aggregate of cells extending radially in the tree stem; the tissue of the ray is primarily composed of food-storing parenchyma cells. (See page(s) 662; Sec. 11.8) |
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| Tracheids (longitudinal) | the predominating cell found in softwoods; tracheids have the function of conduction and support. (See page(s) 662; Sec. 11.8) |
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| Wood vessel | a tubular structure formed by the union of smaller cell elements in a longitudinal row. (See page(s) 662; Sec. 11.8) |
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| Microfibrils | elementary cellulose-containing structures that form the wood cell walls. (See page(s) 662; Sec. 11.8) |
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| Lumen | the cavity in the center of a wood cell. (See page(s) 662; Sec. 11.8) |