GLOSSARY
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A
ABLATIVE
A material that absorbs heat through a decomposition process called pyrolysis at or near the exposed surface. Top
ACETONE
In an FRP context, acetone is primarily useful as a cleaning solvent for removal of un-cured matrix from applicator equipment and clothing. VERY FLAMMABLE LIQUID.Top
ADDITIVES
Ingredients mixed into matrix to improve properties. Top
ADHESION
The state in which two surfaces are held together at an interface by forces or interlocking action or both. Top
ADHESION FAILURE
A rupture of an adhesive bond that appears to be a separation at the adhesive/adherent interface. Top
ADHESIVE
A bonding substance which creates a molecular attraction, holding tow surfaces together.Top
AGING
The effect, on materials, of exposure to an environment for an interval of time; the process of exposing materials to an environment for an interval of time.Top
AIR SPLICE
The coupling between two roving doffs which is made by a jet of air entwining/snarling two strands together. Air splice is used instead of a knot. Top
AIR VENT
Small outlet, to prevent entrapment of gases. Top
AIR-BUBBLE VOID
Air entrapment within and between the plies of reinforcement; non-interconnected, spherical in shape. Top
ALLOY
Made by mixing traditional polymers, which have already been formed. The mixing results in a single-phase material because the polymers have some interaction that combines them together. The properties of the alloy depend upon the physical interactions of the polymers. Top
AMBIENT
The surrounding environmental conditions such as pressure or temperature. Top
AMORPHOUS
Describes polymers that have no order to their molecules, thus no crystalline component. Top
ANISOTROPIC
The tendency of a material to exhibit different properties in response to stresses applied along axes in different directions.Top
ANISOTROPY OF LAMINATES
The difference of the properties along the directions parallel to the length or width into the lamination planes; or parallel to the thickness into the planes perpendicular to the lamination. Top
ANTI-STATIC AGENTS
Agents which, when added to the moulding material or applied on the surface of the moulded object, make it less conducting (thus hindering the fixation of dust). Top
ANTIMONY TRIOXIDE
An additive used to give special flammability characteristics to a polyester. Top
ARAMID
(Twaron(R)/Kevlar(R)) Aromatic polyamide fibres characterized by excellent flame-resistance, high-temperature, and electrical properties. Aramid fibres are used to achieve high-strength, high-modulus reinforcement in plastic composites. Top
AREAL WEIGHT
The weight of fibre per unit area (width times length) of tape or fabric. Top
ARTIFICIAL WEATHERING
Exposure to laboratory conditions, which may be cyclic, involving changes in temperature, relative humidity, radiant energy, and any other elements found in the atmosphere in various geographical areas. Top
ASH CONTENT
The solid residue remaining after a reinforcing substance has been incinerated (or strongly heated). Top
ASPECT RATIO
The ratio of length to diameter of a fibre. Top
ASTM
American Society of Test Methods. Top
ATOMS
The smallest possible unit of an element, which combines with another to form larger units; i.e., molecules. Top
AUTO- IGNITION TEMPERATURE
The lowest temperature required to initiate or cause self-sustained combustion in the absence of a spark or a flame. Top
AUTOCLAVE
A closed vessel that permits application of pressure and heat used for curing composites. Top
AUTOCLAVE MOULDING
A moulding technique in which an entire assembly (lay up) is placed into an autoclave at 50 to 100 psi, in order to consolidate layers of the part by removing entrapped air and volatiles Top
AUTOMATED TAPE LAYING
A fabrication process in which prepreg tape is laid side by side or overlapped in various configurations to form a structure. Top
AXIAL WINDING
A type of filament winding in which the filaments are parallel to the axis. Top
Twintex®
Twintex® is a hybrid yarn copyright Saint-Gobain Vetrotex International Top
B
BAG MOULDING
A moulding technique in which the composite material is placed in a rigid mould and covered with a flexible bag, with pressure applied by vacuum, autoclave, press, or by inflating the bag. Top
BALANCED LAMINATE
All lamina except those at 0/90( are placed in plus/minus pairs (not necessarily adjacent) symmetrically about the lay up centreline. Top
BARCOL HARDNESS
Hardness value obtained by measuring the resistance to penetration of a sharp steel point under a spring load. The instrument, called the Barcol Impressor, gives a direct reading on a 0-100 scale. The hardness value is often used as a measure of the degree of cure of a plastic. Top
BARE GLASS
Glass (yarns, roving, fabrics) from which the sizing or finish has been removed; also, such glass before the application of sizing or finish. Top
BASKET WEAVE
Woven reinforcement where two or more warp threads go over and under two or more filling threads in a repeat pattern. This weave is less stable than the plain weave but produces a flatter, stronger, more pliable fabric. Top
BATCH (or LOT)
Material made with the same process at the same time having identical characteristics throughout. Top
BEARING AREA
The product of the pin diameter and the specimen thickness. Top
BEARING LOAD
A comprehensive load on an interface. Top
BEARING STRENGTH
The maximum bearing stress that will not fail a composite when applied through a cylindrical fastener surface. Top
BEARING STRESS
Applied load divided by bearing area (hole diameter times thickness). Top
BEND TEST
A test of ductility by bending or folding usually with steadily applied forces. In some instances the test may involve blows to a specimen having a cross section that is essentially uniform over a length several times as great as the largest dimension of the cross section. Top
BI-DIRECTIONAL LAMINATE
A reinforced plastic laminate with the fibres oriented in two directions in the plane of the laminate; a cross laminate. Top
BIAS CUT
Fabric cut at an angle (45o) to the warp & fill fibres. Top
BIAS FABRIC
A fabric in which warp and fill fibres are at an angle to the length. Top
BIAXIAL WINDING
In filament winding, a type of winding in which the helical band is laid in sequence, side by side, with the crossover of the fibres eliminated. Top
BINDER
The matrix or cementing constituent of a plastic compound which holds the other components together; the agent applied to glass mat or preforms to bond the fibres prior to laminating or moulding. Top
BLEEDER CLOTH
A layer of woven or non-woven material, not a part of the composite, that allows excess gas and matrix to escape during vacuum bagging. Top
BLEEDER PLY
Layer of porous material placed in a vacuum bag to absorb excess matrix and allow air and gas to escape. Top
BLEEDOUT
The excess liquid matrix appearing at the surface, primarily occurring during filament winding. Top
BLEND
Made by mixing traditional polymers which have already formed. The mixing results in a multi-phase system. Physical interactions between the polymers are responsible for the properties of the blend. Top
BLISTER
Undesirable rounded elevation of the surface of a plastic, whose boundaries may be more or less sharply defined, resembling in shape a blister on the human skin. The blister may burst and become flattened. Top
BMC
Bulk Moulding Compound. Top
BOND PLY
The ply or fabric patch that comes in contact with the honeycomb core during repair. Top
BOND STRENGTH
The amount of adhesion between bonded surfaces; a measure of the stress required to separate a layer of material from the base to which it is bonded. The amount of adhesion between bonded surfaces. Top
BORON fibre
A fibre usually of a tungsten-filament core with elemental boron vapour deposited on it to impart strength and stiffness. Top
BRAID
A system of three or more yarns which are interwoven in such a way that no two yarns are twisted around each other. Top
BRAID ANGLE
The acute angle measured from the axis of braiding. Top
BRAID, THREE-DIMENSIONAL
Braided fabric with one or more braiding yarns in the through thickness direction. Top
BRAID, TWO-DIMENSIONAL
Braided fabric with no braiding yarns in the through thickness. Top
BRAIDED, TRIAXIAL
A biaxial braided fabric with laid in yarns running in the axis of braiding. Top
BRAIDING
Weaving fibres into a tubular shape. Top
BREAKOUT
Separation or breakage of fibres when the edges of a composite part are drilled or cut. Top
BREATHER
A loosely woven material that does not come in contact with the matrix but serves as a continuous vacuum path over a part in production. Top
BRIDGING
Fabric reinforcement extended over a curved edge that does not come into contact with the rest of the composite. Top
BUCKLING (composite)
A failure mode usually characterized by fibre deflection rather than breaking because of compressive action. Top
BURST STRENGTH
(1) Hydraulic pressure required to burst a vessel of given thickness. Commonly used in testing filament-wound composite structures. (2) Pressure required to break a fabric by expanding a flexible diaphragm or pushing a smooth spherical surface against a securely held circular area of fabric. Top
BUTT JOINT
A joint in which parts are joined with no overlap. Top
C
CAD/CAM
Computer-aided design/computer-aided manufacturing. Top
CARBON fibre
Fibres produced by the pyrolysis of organic precursor fibres such as rayon, polyacrylonitrile (PAN), and pitch in an inert atmosphere. The term is often used interchangeably with "graphite"; however, carbon fibres and graphite fibres differ in the temperature at which the fibres are made and heat-treated, and the amount of carbon produced. Carbon fibres typically are carbonized at about 2400(F (1300(C) and assay at 93 to 95% carbon, while graphite fibres are graphitized at 3450 to 5450(F (1900 to 3000(C) and assay at more than 99% elemental carbon. Top
CARBON/CARBON
A composite of carbon fibre in a carbon matrix. Top
CARBONFIBRE REINFORCED PLASTICS (CFRP)
Term used to designate carbon fibre reinforced composites. Top
CAROXYL
The chemical group characteristic of organic acids, which are incorporated into the polyester reaction process. Top
CASTING
The process of pouring a mixture of matrix, fillers and/or fibres into a mould as opposed to building up layers through lamination. This technique produces different physical properties from laminating. Top
CATALYST
A substance which changes the rate of a chemical reaction without itself undergoing permanent change in its composition; a substance which markedly speeds up the cure of a compound when added in minor quantity as compared to the amounts of primary reactants. Top
CAUL PLATE
Plate or sheet the same size and shape as the composite lay-up with which it will be used. The caul plate is placed in immediate contact with the lay-up during curing to transmit normal pressure and provide a smooth surface on the finished part. Top
CAUL SHEET
Plate or sheet the same size and shape used in contact with a composite lay up to transmit normal pressure and temperature during cure. Top
CAULK
An elastic material used to protect joints or connections from external elements, particularly moisture. Top
CAVITY
Depression in mould; the space inside a mould wherein a matrix is poured; the moulded article; which forms the outer surface of the moulded article (often referred to as the die); also, the space between matched moulds. (Depending on number of such depressions, moulds are designated as Single-Cavity or Multiple-Cavity). Top
CENTIPOISE
Measurement of viscosity as compared to water (1 centipoises). Top
CERAMIC-MATRIX COMPOSITES
Materials consisting of a ceramic or carbon fibre surrounded by a ceramic matrix, usually SiC (silicon carbide). Top
CHAIN-GROWTH POLYMERIZATION
One of the two principal polymerization mechanisms. In chain-growth polymerization, the reactive groups are continuously regenerated during the growth process. Once started, the polymer molecule grows rapidly by a chain of reactions emanating from a particular reactive initiator which may be a free radical, cat ion or anion. Top
CHALKING
Dry, powder-like appearance or deposit on gel coat surface. Top
CHEMICAL VAPOR DEPOSITION (CVD)
A process in which desired reinforcement material is deposited from vapour phase onto a continuous core; boron on tungsten, for example. Top
CIRCUIT
One complete traverse of the fibre feed mechanism of a filament-winding machine. Top
CIRCUMFERENTIAL WINDING
A type of filament winding in which the filaments are perpendicular to the axis. Top
CLOTH
another word for fabric, which can be a woven, knitted or processed yarn in another way. Top
COEFFICIENT of EXPANSION (COE)
Measure of the change in length or volume of an object. Top
COEFFICIENT of THERMAL EXPANSION
A material's fractional change in length for a given unit change of temperature. Top
COEFFICIENT OF VARIATION
The ratio of the population (or sample) standard deviation to the population (or sample) mean. Top
COHESION
Tendency of a single substance to adhere to itself. Also, the force holding a single substance together. Top
COIN TAP
Tapping a laminate with a coin in different spots to detect a change in sound, indicating the presence of a defect that may require repair. Top
COLD PRESS MOULDING
Compression Moulding – A technique for moulding thermoplastic material in which a part is shaped by placing the preheated fibre and matrix into an open mould cavity, closing the mould fast, and wait until the material has achieved its final form. Top
COLOR STABILITY
The ability of a surface coating or pigment to resist degradation due to environmental exposure. Top
COMMINGLED YARN
A hybrid yarn made with two types of material intermingled in a single yarn; for example, thermoplastic filaments intermingled with carbon filaments to form a single yarn. Top
COMPATIBLE
The ability of different matrix systems to be processed in contact with each other without degradation of end product properties. Top
COMPOSITE
A homogeneous material created by the synthetic assembly of two or more materials (a selected filler or reinforcing elements and compatible matrix binder) to obtain specific characteristics and properties. Composites are subdivided into classes on the basis of the form of the structural constituents; Laminar: Composed of layer or laminar constituents; Particular: The dispersed phase consists of small particles; Fibrous: The dispersed phase consists of fibres; Flake: The dispersed phase consists of flat flakes; Skeletal: Composed of a continuous skeletal matrix filled by a second material. Top
COMPOUND
An intimate mixture of polymer or polymers with all the materials necessary for the finished product. Top
COMPRESSION MOULD
A mould which is open when the material is introduced and which shapes the material by heat and by the pressure of closing. See also Compression moulding. Top
COMPRESSION MOULDING
A technique for moulding thermo set plastics in which a part is shaped by placing the fibre and matrix into an open mould cavity, closing the mould, and applying heat and pressure until the material has cured or achieved its final form. Top
COMPRESSIVE MODULUS
A mechanical property description which measures the compression of a sample at a specified load. Top
COMPRESSIVE STRENGTH
The ability of a material to resist a force that tends to crush; the crushing load at the failure of a specimen divided by the original sectional area of the specimen. Top
CONDUCTIVITY
Reciprocal of volume resistivity; the conductance of a unit cube of any material. Top
CONNECTION
Where two panels are attached to each other or a panel is attached to the building. Top
CONSOLIDATION
A processing step that compresses fibre and matrix to reduce voids and achieve a desired density using of heat and pressure. Top
CONTAMINANT
Impurity or foreign substance that affects one or more properties of composite material, particularly adhesion. Top
CONTINUOUS FILAMENT
An individual , small-diameter reinforcement that is flexible and indefinite in length. Top
CONTINUOUS HEAT RESISTANCE
This is the maximum temperature the material should be subjected to in a continuous application. Below this temperature the material is acceptable. Above this temperature the material may decompose, melt, or otherwise fail in an application. Units - degrees Fahrenheit ((F) - degrees Centigrade ((C). Higher numbers mean that the material can be used continuously at higher temperatures. Top
CONTINUOUS LAMINATING
A process for forming panels and sheeting in which fabric(s) and layers in a build-up is passed through heating zones and cooling zones, all under pressure, for consolidation. Top
CONTINUOUS ROVING
Parallel filaments coated with sizing, gathered together into single or multiple strands, and wound into a cylindrical package. It may be used to provide continuous reinforcement in woven roving, filament winding, pultrusion, prepregs, or high-strength moulding compounds. Top
CONTINUOUS-FILAMENT YARN
Yarn that is combined by two or more continuous filaments into a single continuous strand. Top
COPOLYMER
A large chemical chain composed of two or more dissimilar groups. Top
CORE
The central component of a sandwich construction to which the sandwich faces or skins are attached; also, part of a complex mould that forms undercut parts. Top
CORE CRUSH
Compression damage of the core. Top
CORE DEPRESSION
A gouge or indentation in the core material. Top
CORE ORIENTATION
Used on a honeycomb core to line up the ribbon direction, thickness of the cell depth, cell size and transverse direction. Top
CORE SPLICING
Joining two core segments by bonding them together. Top
COUPLING AGENT
Any chemical substance designed to react with both the reinforcement and matrix phases of a composite material to form or promote a stronger bond at the interface; a bonding link. Top
COWOVEN FABRIC
A reinforcement fabric woven with two different types of fibres in individual yarns; for example, thermoplastic fibres woven side by side with carbon fibres. Top
CRAZING
Fine cracks, which may extend in a network on or under the surface of a plastic material. Top
CREEL
A device for holding the required number of roving balls or supply packages in desired position for unwinding onto the next processing step. Top
CREEP
The change in dimension of a plastic under load over a period of time, not including the initial instantaneous elastic deformation. (Creep at room temperature is called 'cold flow.') Top
CREEP, RATE OF
The slope of the creep-time curve at a given time. Top
CRIMP
A fibre's waviness, which determines the capacity of the fibre to cohere. Top
CRITICAL LENGTH
The minimum length of a fibre necessary for matrix shear loading to develop fibre ultimate strength by matrix. Top
CROSS LAMINATED
Material laminated so that some of the layers are oriented at various angles to the other layers with respect to the laminate grain. A cross-ply laminate usually has plies oriented only at 0/90. Top
CROSSPLY
Any filamentary laminate which is not uniaxial. Same as Angleply. In some references, the term cross ply is used to designate only those laminates in which the laminate are at right angles to one another, while the term angle ply is used for all others. Top
CRYSTALLINITY
The quality of having a molecular structure with atoms arranged in an orderly, three-dimensional pattern. Top
CYCLE
The complete, repeating sequence of operations in a process or part of a process. In moulding, the cycle time is the period (or elapsed time) between a certain point in one cycle and the same point in the next. Top
D
DAMAGE TOLERANCE
A measure of the ability of structures to retain load-carrying capability after exposure to sudden loads (for example, ballistic impact). Top
DAMPING
Diminishing the intensity of vibrations. Top
DAYLIGHT
The distance in the open position, between the moving and fixed tables or the platens of a hydraulic press. In the case of a multi-daylight press, daylight is the distance between adjacent platens. Top
DEBOND
An unplanned non-adhered or un-bonded region in an assembly. Top
DECITEX
A numbering system for yarn and filament in which yarn number is equal to weight in grams of 10000 meters of yarn. Top
DEEP-DRAW MOULD
A mould having a core which is long in relation to the wall thickness. Top
DEFLECTION TEMPERATURE UNDER LOAD
The temperature at which a simple beam has deflected a given amount under load (formerly called heat distortion temperature). Top
DEFORMATION UNDER LOAD
The dimensional change of a material under load for a specific time following the instantaneous elastic deformation caused by the initial application of the load. (Also, 'cold flow' or 'creep'.) Top
DEGRADATION
A deleterious change in chemical structure, physical properties or appearance. Top
DELAMINATE: DELAMINATION
To split a laminated plastic material along the plane of its layers. Physical separation or loss of bond between laminate plies. Top
DEMOULD
To remove a part from a tool, or a tool from an intermediate model. Top
DENSITY
This is defined as the weight of a material per unit volume. Units - grams/cubic centimetre. Higher numbers indicate heavier materials. Top
DENSITY, fibres
Mass per unit volume of the solid matter of which a fibre is composed, measured under specified conditions. Top
DEVIATION
Variation from a specified dimension or requirement, usually defining the upper and lower limits. Top
DIELECTRIC
A non-conductor of electricity. The ability of a material to resist the flow of an electric current. Top
DIELECTRIC CONSTANT
The ratio of the capacity of a condenser having a dielectric constant between the plates to that of the same condenser when the dielectric is replaced by a vacuum; a measure of the electrical charge stored per unit thickness at unit potential. Top
DIELECTRIC STRENGTH
1) This is an electrical property and gives an indication of how well the material acts as an electrical insulator. It describes how much of an electrical voltage can be built up on one side of the material before it is communicated to the other side. Units - Volts per mil of thickness (volts/mil). Higher numbers indicate materials which are better insulators. C means that the material conducts electricity and therefore has no dielectric strength. 2) The average potential per unit thickness at which failure of the dielectric material occurs. Top
DIMENSIONAL STABILITY
Capability of an item to maintain its constructed dimensions without distorting. Top
DIRECT ROVING
A roving made directly at the bushing that does not go through a roving process. Typical characteristics are: single-end roving, coreless, 6-inch diameter centres and no catenaries. Top
DISPERSION
The means of incorporating pigments into a fluid. Top
DISTRIBUTION
A formula which gives the probability that a value will fall within prescribed limits. Top
DRAPE
The ability of textiles to conform to an irregular shape; textile conformity. Top
DRY fibre AREA
Area of fibre not totally encapsulated by matrix. Top
DRY SPOT
Area of incomplete surface film on laminated plastics; in laminated glass, an area over which the interlayer and the glass have not become bonded. Top
DRY WINDING
A type of filament winding in which pre-impregnated roving is used. Top
DUCTILITY
The ability of a material to deform plastically before fracturing. Top
DUPLICATION MOULD
A mould made by casting over or duplicating another article. Top
E
E-GLASS
"Electrical glass" A borosilicate glass; the type most used for glass fibres for reinforced plastics; -suitable for electrical laminates because of its high resistivity. (Also called 'electrical glass.') Top
EJECTION / DEMOULDING
The process of removing a moulding from the moulding impression; by mechanical means, by hand, or by the use of compressed air. Top
EJECTION PLATE
A metal plate used to operate ejector pins; designed to apply a uniform pressure to them in the process of ejection. Top
ELASTIC DEFORMATION
The part of the total strain in a material under stress that recovers upon removal of the stress. Top
ELASTIC LIMIT
The greatest stress which a material is capable of sustaining without permanent strain remaining upon the complete release of the stress. A material is said to have passed its elastic limit when the load is sufficient to initiate plastic, or non-recoverable, deformation. Top
ELASTICITY
The property of materials to recover their original size and shape after deformation. Top
ELASTOMER
A polymeric material which has a high modulus of elasticity and toughness. Urethane elastomer is an example. Top
ELONGATION
Standard measure for the amount a sample can stretch as a percentage of original length before it fails or breaks. Top
ELONGATION AT BREAK
Elongation recorded at the moment of rupture of the specimen, often expressed as a percentage of the original length. Top
END
A strand of roving consisting of a given number of filaments gathered together. Top
END COUNT
An exact number of ends supplied on a ball or roving. Top
EXTENSOMETER
A device for measuring linear strain. Top
F
FABRIC, NONWOVEN
A material formed from fibres or yarns without interlacing. Top
FABRIC, WOVEN
A material constructed of interlaced yarns, fibres, or filaments. Top
FATIGUE
The failure or decay of mechanical properties after repeated applications of stress.Top
FATIGUE LIFE
The number of cycles of deformation required to bring about failure of the test specimen under a given set of oscillating conditions. Top
FATIGUE LIMIT
The stress below which a material can be stressed cyclically for an infinite number of times without failure. Top
FATIGUE STRENGTH
The maximum cyclic stress a material can withstand for a given number of cycles before failure occurs; the residual strength after being subjected to fatigue. Top
FEA
Finite element analysis, a process of selecting the optimum combination of materials in a composite based on software analysis. Top
FELT
a fibrous material made up of interlocking fibres by mechanical or chemical reaction, pressure or heat. Felts may be made of cotton, glass, or other fibres. Top
FEMALE MOULD
A concave mould used to precisely define the convex surface of a moulded part. Top
FIBRE
Very small normally round cross sections (in micron)of various materials. For commingling process endless filamntes are used. More fibres together form a yarn or roving. Also known as FIBER in USA. Top
FIBRE ARCHITECTURE
The design of a fibrous preform or part in which the fibres are arranged (braided, stitched, woven, etc.) in a particular way in order to achieve the desired result. Top
FIBRE CONTENT
Amount of fibre present in a composite expressed as a ratio to the matrix. The ratio can either be by volume or by weight. Top
FIBRE DIAMETER
The measurement (expressed in micron) of the diameter of individual filaments. Top
FIBRE GLASS
Fibres made by continuing Glass filaments.Top
FIBRE ORIENTATION
Fibre alignment in a laminate where the majority of fibres are in the same direction, resulting in a higher strength in that direction. Top
FIBRE PLACEMENT
A continuous process for fabricating composite shapes with complex contours and/or cut-outs by means of a device that lays pre-impregnated fibres (in tow form) onto a non-uniform mandrel or tool. It differs from filament winding (below) in several ways: there is no limit on fibre angles; compaction takes place on-line via heat, pressure, or both; and fibres can be added and dropped as necessary. The process produces more complex shapes and permits a faster put-down rate than filament winding. Top
FIBRE REINFORCED PLASTICS (FRP)
Term used to designate glass fibre reinforced composites. Top
FIBRE SYSTEM
The type and arrangement of fibrous material which comprises the fibre constituent of an advanced composite. Examples of fibre systems are collimated filaments or filament yarns, woven fabric, randomly oriented short-fibre ribbons, random fibre mats, whiskers, etc. Top
FILAMENT
The smallest unit of a fibrous material. The basic units formed during spinning and which are gathered into strands of fibre for use in composites. Filaments usually are of extreme length and of very small diameter. Filaments normally are not used individually. Some textile filaments can function as a yarn when they are of sufficient strength and flexibility. Top
FILAMENT WINDING
A process for fabricating a composite structure in which continuous reinforcements (filament, wire, yarn, tape, or other) either previously impregnated with a matrix material or impregnated during the winding are placed over a rotating and removable form or mandrel in a previously prescribed way to meet certain stress conditions. Generally the shape is a surface of revolution and may or may not include end closures. When the right number of layers are applied the wound form is cured and the mandrel removed, if it is not manufactured in a continuing laminating process. Top
FILAMENT WOUND
Pertaining to an object created by the filament winding method of fabrication. Top
FILAMENT YARN
A yarn composed of continuous filaments assembled with or without twists. Top
FILAMENTARY COMPOSITES
A major form of advanced composites in which the fibre constituent consists of continuous filaments. Specifically, a filamentary composite is a laminate comprised of a number of lamina, each of which consists of a nonwoven, parallel, uniaxial, planar array of filaments (or filament yarns) embedded in the selected matrix material. Individual lamina are directionally oriented and combined into specific multiaxial laminates for application to specific envelopes of strength and stiffness requirements. Top
FILAMENTS
Individual glass fibres of indefinite length, usually as pulled from a stream of molten glass flowing through an orifice of the bushing. In the operation, a number are gathered together to make a strand or end of roving or yarn. Top
FILL
yarn running from selvage to selvage at right angles to the warp in a woven fabric. Top
FILL THREADS
Also known as the weft. These are the crosswise fibres woven at 90 degrees to the warp fibres. Top
FILLER
A relatively inert material added to a plastic mixture to reduce cost, to modify mechanical properties, to serve as a base for colour effects, or to improve the surface texture. Top
FILLER PLY
Additional patch to fill in a depression in repair or to build up an edge. Top
FILM ADHESIVE
An adhesive in the form of a thin, dry, matrix film with or without a carrier, commonly used for adhesion between layers of laminates. Top
FINISH
Material applied to fibres, after sizing is removed, to improve matrix-to-fibre coupling. Top
FINITE ELEMENT ANALYSIS (FEA)
A process of selecting the optimum combination of materials in a composite based on software analysis. Top
FIRE POINT
The lowest temperature at which a liquid in an open container will give off enough vapours to continue to burn once ignited. Fire point generally is only slightly higher than flash point. Top
FLAME RETARDENT matrix
A matrix which is compounded with certain chemicals to reduce or eliminate its tendency to burn. Top
FLAME RETARDENTS
Certain chemicals that are used to reduce or eliminate a matrices tendency to burn. Top
FLAMMABILITY
A measure of how fast a material will burn under controlled conditions. Top
FLANGE
An extension around the perimeter of a mould or part for the purpose of remoulding, stiffening or connecting two components. Top
FLASH POINT
The lowest temperature at which a substance gives off enough vapours to form a flammable or ignitable mixture with air near the surface of the substance being tested. Top
FLEXURAL MODULUS
This is a number associated with the stiffness of materials. It is used to calculate how far a bar will bend when a bending load is applied to it. Units are normally millions of pounds per square inch. (106 Psi) - Giga Pascal (gPa). Higher numbers for materials mean that they are more resistant to deflection when equal thickness are being compared. Top
FLEXURAL STRENGTH
The resistance of a material to being broken by bending stresses; the strength of a material in bending, expressed as the tensile stress of the outermost fibres of a bent test sample at the instant of failure. (With plastics, this value is usually higher than the straight tensile strength.) Top
FLOW
The movement of matrix under pressure, allowing it to fill all parts of a mould; flow or creep - the gradual but continuous distortion of a material under continued load, usually at high temperature. Top
FOAM
A lightweight, cellular plastic material containing gas-filled voids. Typical foams include urethane, PVC and polyester. Top
FOAM-IN-PLACE
The process of creating a foam by the combination of two liquid polymers. See In-Situ. Top
FRACTURE
A rupture of the surface of a laminate because of external or internal forces, with or without complete separation. Top
FRACTURE DUCTILITY
The true plastic strain at fracture. Top
FRACTURE TOUGHNESS
A measure of the damage tolerance of a material containing initial flaws or cracks. Top
FREE RADICALS
Highly reactive molecular fragments capable of initiating chemical reactions, such as polymerization of polyester matrices. Top
FRP
Fibrous-glass reinforced plastic; a general term covering any type of plastic reinforced cloth, mat, strands, or any other form of fibrous glass. Top
G
GFRP
Glass fibre-reinforced plastic, polymer or polyester. Top
GLASS
An inorganic product of fusion which has cooled to a rigid condition without crystallizing. Top
GLASS CLOTH
Conventionally-woven glass fibre material (see Scrim). Top
GLASS FIBRES
A fibre spun from an inorganic product of fusion which has cooled to a rigid condition without crystallizing. Top
GLASS RICH
An area of moulded part that has an overabundance of glass reinforcement. The reinforcement may appear dry and unwet with the matrix. Top
GLASS TRANSITION
The reversible change in an amorphous polymer between a viscous or rubbery condition and a hard, relatively brittle one. Top
GLASS-TRANSITION TEMPERATURE (Tg)
The approximate temperature at which increased molecular mobility results in significant changes in properties of a cured matrix. The measured value of Tg can vary, depending on the test method. Top
GLASS/matrix RATIO
The amount of glass by weight compared to the amount of matrix by weight in a finished laminate or moulding. Top
GRAPHITE FIBRES
See Carbon Fibres. Top
GRAPHITIZATION
The process of pyrolization at very high temperatures (as high as 5400(F) that converts carbon to its crystalline allotropic form. Top
GRP
Glass-reinforced plastic, polymer, polyester. Top
GUIDE PIN
A pin, which guides mould halves into alignment on closing. Top
H
HARD TOOL
A tool made of metallic or any "hard" material that is generally impervious to damage during normal use. Top
HEAT-DISTORTION TEMPERATURE
Temperature at which a test bar deflects a certain amount under specified temperature and a sated load. Top
HONEYCOMB
Material manufactured in, usually, hexagonal cells that serve as a core material in sandwich constructions. Honeycomb may be metallic, matrix-impregnated or polymer materials in a rigid, open structure. Top
HONEYCOMB CORE
Strips of paper, plastic metal, etc., joined together to form a honeycomb pattern. Used as a lightweight core in sandwich mouldings. Top
HOOP STRESS
Circumferential stress in a cylindrically shaped part as a result of internal or external pressure. Top
HORIZONTAL SHEAR
Sometimes used to indicate interlaminar shear. Top
HOT BOND REPAIR
Repair made on a hot-patch bonding machine to cure and monitor curing. Typically includes heat and vacuum source. Top
HUMIDITY
Moisture content of the air. Top
HUMIDITY, RELATIVE
The ratio of the pressure of water vapour present to the pressure of saturated water vapour at the same temperature. Top
HYBRID COMPOSITE
A composite with two or more types of matrix, systems or reinforcing fibres . Top
HYBRID YARN
A hybrid yarn is a textured or a commingled yarn consisting of structural fibres and thermoplastic polymer fibres. The hybrid yarn is a so-called prostpreg material (opposite prepreg) since the fibres are impregnated with the matrix in a post-process. The hybrid yarn is "soft" and drape able, and therefore very suitable for producing fibre preforms by almost any textile technology. Top
HYDRAULIC PRESS
A press in which the moulding force is created by the pressure exerted on a fluid. Top
HYDROPHOBIC
Moisture resistant capability, moisture repelling. Top
HYGROSCOPIC
Capable of absorbing and retaining atmospheric moisture. Top
I
IGNITION LOSS
The difference in weight before and after burning; as with glass, the burning off of the binder or size. Top
ILSS
See INTERLAMINAR SHEAR STRENGTH. Top
IMPACT STRENGTH
The ability of a material to withstand shock loading; the work done in fracturing a test specimen in a specified manner under shock loading. Top
IMPREGNATE
In reinforced plastics, the saturation of the reinforcement with a matrix. Top
IMPREGNATED FABRIC
See Prepreg. Top
IN-SITU
In the position which it will finally occupy, e.g. moulding or forming foam. Top
INCLUSION
A physical and mechanical discontinuity occurring within a material or part, usually consisting of solid, encapsulated foreign material. Inclusions are often capable of transmitting some structural stresses and energy fields, but in a noticeably different manner from the parent material. Top
INHIBITOR
A substance which retards a chemical reaction. Top
INSERT
An integral part of a plastics moulding consisting of metal or other material which may be moulded into position or pressed into the moulding after the moulding is completed. Top
INTEGRAL COMPOSITE STRUCTURE
Composite structure in which several structural elements, which would conventionally be assembled by bonding or with mechanical fasteners after separate fabrication, are instead laid up and cured as a single, complex, continuous structure: e.g., spars, ribs, and one stiffened cover of a wing box fabricated as a single integral part. The term is sometimes applied more loosely to any composite structure not assembled by mechanical fasteners. Top
INTEGRAL HEATING
A system in which heating elements are built into a tool, forming part of the tool and usually eliminating the need for an oven or autoclave as a heat source. Top
INTERFACE
The junction point or surface between two different media; on glass fibres, the contact area between glass and sizing or finish; in a laminate, the contact area between the reinforcement and the laminating matrix. Top
INTERLAMINAR SHEAR
The shearing force tending to produce displacement between two lamina along the plane of their interface; usually the weakest element of a composite. Top
INTERLAMINAR SHEAR STRENGTH
The maximum shear stress existing between layers of a laminated material. Top
INTRALAMINAR
Descriptive term pertaining to some object (e.g., voids), event (e.g., fracture), or potential field (e.g., temperature gradient) existing entirely within a single, lamina without reference to any adjacent lamina. Top
ISO
Short for International Standards Organization or abbreviated terminology for the isophthalic acid type matrices . Top
ISOTROPIC
Having uniform properties in all directions-independent of the direction of load application. Top
IZOD IMPACT TEST
A destructive test designed to determine the resistance of a plastic to the impact of a suddenly applied force. Top
J
JIG
Any fixture for holding parts in position, while joining them together or to maintain their shape. Top
JOINT
A line or distinction formed when two panels are connected. Also referred to as a seam. Top
K
KEVLAR
Trademark of DuPont for aramid fibres used as a reinforcement fibre. Top
KNITTING
A method of constructing fabric by interlocking series of loops of one or more yarns. Top
L
Technique for producing long runs of identical parts with two finished sides. Top
LAMINA
A single ply or layer in a laminate made up of a series of layers. Top
LAMINATE
To unite layers of material by a bonding material usually with pressure and heat. Top
LAMINATE ORIENTATION
The configuration of a cross-plied composite laminate with regard to the angles of cross-plying, the number of laminate at each angle, and the exact sequence of the lamina lay-up. Top
LAMINATE PLY
One layer of a laminated product. Top
LAND
The portion of a mould which provides the separation or cut-off of the flash from the moulded article; in the screw of an extruder, the bearing surface along the top of the flights; in an extrusion die, the surface parallel to the flow of material; in a semi-positive or flash mould, the horizontal bearing surface; in a two-piece mould, a platform build up to the split line. Top
LAP JOINT
A joint made by bonding overlapped portions of two adherents. Top
LAY-UP
As used in reinforced plastics, the reinforcing material place in position in the mould; the process of placing the reinforcing material in position in the mould; the matrix-impregnated reinforcement; a description of the component materials, geometry, etc. of a laminate. Top
LAYER
A single ply of lay up or laminate. Top
LENGTHWISE DIRECTION
Refers to the cutting of specimens and to the application of loads. For rods and tubes, lengthwise is the direction of the long axis. For the other shapes of materials that are stronger in one direction than in the other, lengthwise is the direction that is stronger. For materials that are equally strong in both directions, lengthwise is an arbitrarily designated direction that may be with the grain, direction of flow in manufacture, longer direction, etc. Top
LIQUID-CRYSTAL POLYMERS
A newer type of thermoplastic, melt processible, with high orientation in moulding, improved tensile strength, and high-temperature capability. Top
LOAD-DEFLECTION CURVE
A curve in which the increasing flexural loads are plotted on the ordinate axis and the deflections caused by those loads are plotted on the abscissa axis. Top
LOFT
The height of the dry lay-down "laminate". Top
LOI
See LOSS ON IGNITION. Top
LOSS ON IGNITION
Weight loss, usually expressed as percent of total, after burning off an organic sizing from glass fibres, or an organic matrix from a glass fibre laminate. Top
LOW-PRESSURE LAMINANTS
In general, laminates moulded and cured in the range of pressures from 25 atm down to and including pressure obtained by the mere contact of the plies. Top
LPET
LPET is an amorphous thermoplastic polyester (PET type), which is modified to melt at 160-180° C. It is shaped and will wet the surface of reinforcement fibres at 200-230° C, and its maximum continuous operating temperature is around 60° C. It exhibits high chemical resistance. LPET-based COMFIL® materials are used in the industry.
MOISTURE ABSORPTION
The pick-up of water vapour from air by a material. It relates only to vapour withdrawn from the air by a material. Top
MOULD
The cavity into or on which the composition is placed and from which it takes form; to shape parts or finished articles by heat and pressure. Top
M
MALE MOULD
A convex mould where the concave surface of the part is precisely defined by the mould surface. Top
MANDREL
The core around which materials wound to form pipes, tubes, or vessels; in extrusion, the central finger of a pipe or tubing die. Top
MASS
The quantity of matter contained in a specific body. Top
MASTER (Plug)
The permanent tool used to build moulds for the manufacture of parts. Top
MAT
A fibrous material for reinforced plastic consisting of randomly oriented chopped filaments or swirled filaments with a binder; and available in blankets of various widths, weights, and lengths. Top
MAT BINDER
matrix applied to glass fibre and cured during the manufacture of mat, to hold the fibres in place and maintain the shape of the mat. Top
MATCHED METAL MOULDING
A reinforced plastics manufacturing process in which matching male and female metal moulds are used ( similar to compression moulding) to form the part - as opposed to low pressure laminating. Top
MATCHED MOULDS
Two or more tools arranged in a set as a male and female mould. Normally used in a press. Top
MATERIAL ACCEPTANCE
The testing of incoming material to ensure that it meets requirements. Top
MATERIAL QUALIFICATION
The procedures used to accept a material by a company or organization for production use. Top
MATERIAL SYSTEM
A specific composite material made from specifically identified constituents in specific geometric proportions and arrangements and possessed of numerically defined properties. Top
MATRIX
The thermoplastic material in which the fibre of a composite is embedded. Top
MATRIX
A solid, semisolid, or pseudo solid organic material which has an indefinite and often high molecular weight, exhibits a tendency to flow when subjected to stress, usually has a softening or melting range, and usually fractures conchoidally. In reinforced plastics, the material used to bind together the reinforcement material; the "matrix. Top
MATRIX CONTENT
The amount of matrix in a laminate expressed as either a percent of total weight or total volume. Top
MATRIX VISCOSITY
Viscous property of a matrix system or solid to liquid transition resistance to flow, which can be altered by temperature and pressure as necessary to achieve desired flow characteristics. Top
MATRIX-RICH AREA
Space which is filled with matrix and lacking reinforcing material. Top
MATRIX-STARVED
Areas of insufficient matrix, usually identified by low gloss, dry spots or fibre show. Top
MECHANICAL PROPERTIES
The properties of a material that are associated with elastic and inelastic reaction when force is applied, or the properties involving the relationship between stress and strain. Top
MICROCRACKING
Microscopic cracks formed in composites when thermal stresses locally exceed the strength of the matrix. Top
MICRON
One micron = .001 millimetre. Top
MODULUS
A number which expresses a measure of some property of a material: modulus of elasticity, shear modulus, etc.; a coefficient of numerical measurement of a property. Normally use for Young’s Modulus. Top
MODULUS OF ELASTICITY
The ratio of the stress or load applied to the strain or deformation produced in a material that is elastically deformed. If a tensile strength of 30 MPa results in an elongation of one percent, the modulus of elasticity is 30 divided by 0.01, or 3,000 MPa = 3 GPa (Young's Modulus). Top
MOISTURE CONTENT
The amount of moisture in a material determined under prescribed condition and expressed as a percentage of the mass of the moist specimen. Top
MOISTURE EQUILIBRIUM
The condition reached by a sample when it no longer takes up moisture from, or gives up moisture to, the surrounding environment. Top
MONOFILAMENT
A single filament of indefinite length. Monofilaments are generally produced by extrusion. Top
MONOLAYER
The basic laminate unit from which cross-plied or other laminates are constructed. Top
MOULD RELEASE
A wax or polymer compound that is applied to the mould surface which acts as a barrier between the mould and the part, thus preventing the part from the bonding to the mould. Top
MOULD-RELEASE AGENT
A liquid or powder used to prevent sticking of moulded articles in the cavity. Top
MOULDING
The process of using a mould to form a part. Top
MOULDING CYCLE
The period of time occupied by the complete sequence of operations on a moulding press requisite for the production of one set of mouldings; the operations necessary to produce a set of mouldings without reference to the time taken. Top
MOULDING PRESSURE, COMPRESSION
The unit pressure applied to the moulding material in the mould. The area is calculated from the projected area taken at right angles to the direction of applied force and includes all areas under pressure during complete closing of the mould. The unit pressure is calculated by dividing the total force applied by this projected area, and is expressed in atm. Top
MULTIFILAMENT
A yarn consisting of many continuous filaments. Top
NON-CRIMP FABRIC
A textile structure produced by laying the fibres straight and sewing them with a thin thread normally on a multi axial machine. Top
N
NDE
Non-destructive Evaluation. Broadly considered synonymous with NDI. Top
NDI
Non-destructive inspection. A process or procedure for determining material or part characteristics without permanently altering the test subject. NDT and NDE are broadly considered synonymous with NDI. Top
NDT
Non-destructive Testing. A process or procedure for determining the quality or characteristics of a material, part, or assembly without permanently altering the subject or its properties. Top
NEAR-NET SHAPE
A characteristic of a part whose fabricated dimensions are so close to final dimensions that machining or cutting to final shape is not required. Top
NET SHAPE
Part fabrication resulting in final dimensions that do not require machining or cutting. Top
NOMINAL SPECIMEN THICKNESS
The nominal ply thickness multiplied by the number of plies. Top
NON-WOVEN FABRIC
A textile structure produced by bonding or interlocking of fibres, or both, accomplished by mechanical, chemical, thermal, or solvent means and combinations thereof. Top
O
OLIGOMER
A polymer consisting of only a few monomer units such as a dimer, trimer, etc., or their mixtures. Top
ONE-OFF
A fabrication process in which a single part is fabricated. Top
ORIENTED MATERIALS
Composites whose constituents are aligned in a particular way. Top
P
PAN
See Polyacrylonitrile. Top
PAN fibres
Reinforcement fibre derived from the controlled pyrolysis of poly(acrylonitrile) fibre. Top
PARALLEL-LAMINATED
Laminated so that all layers of material are oriented approximately parallel with respect to the grain or strongest direction in tension. Also called unidirectional. This pattern allows the highest loading of reinforcement, but gives maximum strength in only one direction. Top
PART CONSOLIDATION
A process of composites fabrication in which multiple discrete parts are designed and fabricated together into a single part, thus reducing the number of fabricated parts and the need to join those parts together. Top
PATTERN
The initial model for making fibreglass moulds. Top
PIGMENT
the ingredient used in gel coats to impart colour. Top
PINHOLE
A tiny hole in the surface of, or through, a plastic material; usually occurring in multiples. Top
PITCH
A residual petroleum product used in the manufacture of certain carbon fibres. Top
PLASTIC DEFORMATION
Change in dimensions of an object under load that is not recovered when the load is removed; opposed to elastic deformation. Top
PLIED YARN
A yarn formed by twisting together two or more single yarns in one operation. (Synonyms: folded yarn, formed yarn.) Top
PLUG
The permanent tool used to build moulds for the manufacture of parts. See Master. Top
PLY
The number of single yarns twisted together to form a plied yarn; one of the layers that make up a stack or laminate. Top
PLY SCHEDULE
Lay-up of individual plies or layers to form a laminate. Plies may be arranged in alternating fibre orientation to produce multi-directional strength in a part. Top
POISSON'S RATIO
The ratio of transverse strain to axial strength during axial load. Top
POLYACRYLONITRILE (PAN)
A product used as a base material in the manufacture of certain carbon fibres. Top
POLYAMIDE
PA, a polymer in which the structural units are linked by amide or thioamide groupings. Many polyamides are fibre-forming. Top
POLYESTERS
A polyester is a polymer (a chain of repeating units) where the individual units are held together by ester linkages. Here the thermoplastic matrices are produced by polymerisation of diols and an acid. Examples are PBT and PET. Top
POLYMER
A very large molecule formed by combining a large number of smaller molecules, called monomers, in a regular pattern. Top
POLYMERIZATION
A chemical reaction in which the molecules of monomers are linked together to form polymers. Top
POROSITY
Small air bubbles in the gel coat film; too numerous to count. Generally smaller in size than pinholes. Top
POSITIVE MOULD
A mould designed to apply pressure to a piece being moulded with no escape of material. Top
POSTPREG
Prostpreg materials (opposite prepreg) are materials where the fibres are impregnated with the matrix in a post-process (see hybrid yarn). Top
PRECURE
The full or partial setting of a matrix or adhesive before the clamping operation is complete or before pressure is applied. Top
PRECUSOR
For carbon fibres, the rayon, PAN, or pitch fibres from which carbon fibres are made. Top
PREFORM
A preshaped fibrous reinforcement of mat or cloth which is formed to the desired shape on a mandrel or mock-up or preproduced prior to being placed in a mould press. Also, a compact "pill" formed by compressing premixed material to facilitate handling and control of uniformity of charges for mould loading. Top
PREHEATING
The heating of compound prior to moulding or casting in order to facilitate the operation or to reduce the moulding cycle. Top
PREPREG
Ready-to-mould material in sheet form which may be cloth, mat, or paper impregnated with matrix and stored for use. Then supplied to the fabricator who lays up the finished shape and completes the manufacture with heat and pressure. Top
PRESSURE
The force or load per unit area. Top
PRESSURE BAG
A membrane which conforms to the inside of a laminate laid up on a mould. The membrane or bag is then inflated applying pressure, which consolidates and densifies the laminate. Top
PRESSURE-BAG MOULDING
A moulding technique in which a flexible bag is placed over the contact lay up in the mould, sealed, and clamped in place, and pressure applied by compressed air, which forces the bag against the part while the part moulds. Top
PRINT THROUGH
"Telegraphing" of the image of reinforcement strands through the top layer. Top
PROTOTYPE
Process of creating a test part not intended for commercial release that establishes design, material and fabrication parameters for a new product. May entail multiple iterations to arrive at final/commercial part design. Top
PULTRUSION
Reversed "extrusion" of hybrid yarns in the manufacture of rods, tubes and structural shapes of a permanent cross-section. The hybrid yarn, after passing through heating, is drawn through a die to form the desired cross-section. Top
Q
QUASI-ISOTROPIC
Approximating isotropy by orientation of piles in several directions. Top
R
RAMPING
A gradual, programmed increase/decrease in temperature or pressure to control the heating up or cooling of composite parts. Top
REINFORCED PLASTIC
A plastic with relatively high stiffness or very high strength fibres embedded in the composition. This improves some mechanical properties over that of the base matrix. Top
REINFORCEMENT
A strong inert material bonded into a plastic to improve its strength, stiffness, and impact resistance. Reinforcements are usually long fibres of glass, asbestos, sisal, cotton, etc., in woven or nonwoven form. To be effective, the reinforcing material must form a strong adhesive bond with the matrix. Top
RELEASE AGENT
A material which is applied in a thin film to the surface of a mould to keep the matrix from bonding to the mould. Top
RELEASE FILM
An impermeable film layer that does not bond to the composite during cure. Top
REVERSE IMPACT TEST
In which one side of a sheet of material is struck by a pendulum or falling object and the reverse side is inspected for damage. Top
REVERSE SANDWICH LAY-UP
A laminate arrangement in which the reinforced mat is laminated between outer layers of other materials. Top
RIB
A reinforcing member of a fabricated or moulded part. Top
RIBBON DIRECTION
On a honeycomb core, the way the honeycomb can be separated. The direction of one continuous ribbon. Top
ROVING (filament winding)
The term roving is used to designate a collection of bundles of continuous filaments either as untwisted strands or as twisted yarns. Top
RTA (Room Temperature Ambient)
An environmental condition 23 degree C at ambient laboratory relative humidity; 2) a material condition where, immediately following consolidation/cure, the material is stored at 23 degree C and at a maximum relative humidity of 60%. Top
RTP
Sometimes used to distinguish reinforced thermoplastic from reinforced thermosetting plastic. Top
RUBBER PLUNGER MOULDING
A variation of the matched-die moulding process which uses a heated metal female mould (or outer half) and a rubber plunger male mould. Applicable for relatively small moulds with modest undercuts where low pressures are involved. Top
S
S-2 GLASS fibre
The Owens Corning trademarked brand of high tensile strength "S" glass fibres. Top
S-GLASS
A family of magnesium-alumina-silicate glasses with a certified chemical composition which conforms to an applicable material specification and which produces high mechanical strength. (ASTM D578-90). Top
SANDWICH CONSTRUCTION
A composite composed of a lightweight core material (usually honeycomb or foamed plastic) to which two relatively thin, dense, high-strength, functional, or decorative skins (also called faces) are adhered. Top
SANDWICH LAY-UP
A lamination composed of two outside layers of reinforced material and an inside layer or layers of honeycomb, other reinforcements, or other light-weight core material. Top
SCRIM
A low cost, non-woven open-weave reinforcing fabric made from continuous filament yarn in an open mesh construction. Top
SEALANT
Applied to a joint in paste or liquid from that hardens in place to form a seal. Top
SECONDARY STRUCTURE
Aircraft or Aerospace structure that is not critical to flight safety. Top
SELF EXTINGUISHING
Ceases to burn when the source of flame is removed. Top
SELVAGE
The narrow edge of woven fabric that runs parallel to the warp. Top
SHEAR
An action or stress resulting from applied forces which causes or tends to cause two contiguous parts of a body to slide relative to each other in a direction parallel to their plane of contact. Inter laminar Shear (ILS). The plane of contact is composed of matrix only. Top
SHEAR EDGE
The cut-off edge of the mould. Top
SHEET MOULDING COMPOUND (SMC)
A ready-to-mould glass fibre reinforced polyester material primarily used in compression moulding. Top
SHELF LIFE
The length of time a material can be stored and continue to meet specification requirements, remaining suitable for its intended use. Top
SHORE HARDNESS
A measure of the resistance of a material to indentation by a spring loaded indenter. A higher number indicates greater resistance. Top
SHRINKAGE
The relative change in dimension between the length measured on the mould when it is cold and the length on the moulded object 24 hours after it has been taken out of the mould. Top
SILICON CARBIDE fibre
A reinforcing fibre with high strength and modulus; density equal to that of aluminium. It is used in organic metal-matrix composites. Top
SIZING
A compound that binds together and stiffens yarn, providing resistance to abrasion during weaving; normally removed and replaced with finish before matrix application. Top
SKIN
A layer of relatively dense material used in sandwich construction on the surface of the core. Top
SLEEVING
A common name for tubular braided fabric. Top
SOLID
The amount of sizing on the glass expressed as a percentage of the total weight. Top
SOLVENT
A liquid used to dissolve and clean materials. Top
SOLVENT RESISTANCE
The non-swelling of a material and, of course, the impossibility for it to be dissolved by the solvent in question. Top
SPEC
Specifications of the properties, characteristics, or requirements a particular material or part must have in order to be acceptable to a potential user of the material or part. Top
SPECIFIC GRAVITY
The ratio of the weight of any volume of a substance to the weight of an equal volume of another substance taken as standard at a constant or stated temperature. Solids and liquids are usually compared with water, and air or hydrogen for gases. Top
SPECIFIC HEAT
(Thermal Capacity) The quantity of heat required to raise the temperature of a kilogram unit of mass one degree Centigrade under specified conditions. Units = Joules/Kilogram Kelvin (J/KgK). Higher numbers means that it takes more input heat energy to raise the temperature of a material. Top
SPECIMEN
An individual piece or portion of a sample used to make a specific test; of specific shape and dimensions. Top
SPLICE
The joining of two ends of the reinforcement fibre yarn or strand, usually by means of air or glue. Top
SPLIT MOULD
A mould in which the cavity is formed of two or more components held together by an outer chase. The components are known as splits. Top
STAPLE
Either naturally occurring fibres or lengths cut from filaments. Top
STIFFNESS
The relationship of load and deformation; a term often used when the relationship of stress to strain does not conform to the definition of Young's modulus. Top
STORAGE LIFE
The period of time during which a liquid matrix or packaged adhesive can be stored under specified temperature conditions and remain suitable for use. (Also "shelf life."). Top
STRAIN
The elastic deformation of a material as a result of stress. Top
STRAND COUNT
The number of strands in a plied yarn; the number of strands in a roving. Top
STRAND INTEGRITY
The degree to which the individual filaments making up the strand or end are held together by the sizing applied. Top
STRANDS
A primary bundle of continuous filaments (or slivers) combined in a single compact unit without twist. Top
STRENGTH, FLEXURAL
The maximum stress that can be borne by the surface fibres in a beam in bending. The flexural strength is the unit resistance to the maximum load prior to failure by bending, usually expressed in MPa. Top
STRESS
The internal force that resists change in size or shape, expressed in force per unit area. Top
STRESS CONCENTRATION
The magnification of applied stress in the region of a notch, void, hole, or inclusion. Top
STRESS CORROSION
Preferential attack of areas under stress in a corrosive environment, where such an environment alone would not have caused corrosion. Top
STRESS CRACK
External or internal cracks in a composite caused by tensile stresses; cracking can be present internally, externally or in combination. Top
STRESS-STRAIN
Stiffness, expressed in pounds per square inch or kilograms per square centimetre, at a given strain. Top
STRESS-STRAIN CURVE
Simultaneous readings of load and deformation, converted to stress and strain, are plotted as ordinates and abscissa, respectively, to obtain a stress-strain diagram. Top
STRUCTURAL ADHESIVE
An adhesive used for transferring loads between adherents. Top
STRUCTURAL BOND
A bond joining load-bearing components of an assembly. Top
STRUCTURAL ELEMENT
A generic element of a more complex structural member (for example, skin, stringer, shear panels, sandwich panels, joints, or splices). Top
SURFACING VEIL
Used with other reinforcing mats and fabrics to enhance the quality of the surface finish. Designed to block out the fibre patterns of the underlying reinforcements. Top
T
TACK
Stickiness of an adhesive or filament reinforced matrix prepreg material. Top
TANGENT MODULUS
The slope of the line at any point on a static stress-strain curve expressed in psi per unit strain. This is the tangent modulus at that point in shear, extension, or compression as the case may be. Top
TAPE
A thin unidirectional prepreg. Top
TAPE LAYING
An automated fabrication process in which prepreg tape is laid side by side or overlapped to form a structure. Top
TENACITY
The term generally used in yarn manufacture and textile engineering to denote the strength of a yarn or of a filament of a given size. Numerically it is the grams of breaking force per decitex unit of yarn or filament size. Tenacity equals breaking strength (grams) divided by decitex. Top
TENSILE ELONGATION
An engineering term referring to the amount of stretch a sample experiences during tensile strain. Top
TENSILE MODULUS
When a bar is pulled in tension, it has to get longer. The tensile modulus is used to calculate how much longer it will get when a certain load is applied to it. Units are normally Giga Pascal (GPa). Higher numbers indicate materials, which will not elongate as much as others when they are being compared under equal tensile loading conditions. Top
TENSILE STRENGTH OR STRESS
The maximum tensile load per unit area of original cross section, within the gage boundaries, sustained by the specimen during a tension test. Tensile load is interpreted to mean the maximum tensile load sustained by the specimen during the test, whether or not this coincides with the tensile load at the moment of rupture. Top
TEX
A unit for expressing linear density, equal to the mass in grams of 1 km of yarn, filament, fibre or other textile strand. Top
THERMAL COEFFICIENT OF EXPANSION
Measures dimensional change of a material when heated or cooled. Top
THERMAL CONDUCTIVITY
This property is known as the K factor. It is a measure of the transfer of heat by conduction. It tells how much heat is transferred from one side of a plate to the other side. Top
THERMAL STRESS CRACKING
Crazing and cracking of some thermoplastic matrices from overexposure to elevated temperatures. Top
THERMOCOUPLE
Wire assembly used with a control device to sense temperature readings. Top
THERMOPLASTICS
A group of plastic materials that become elastic or melt when heated, and return to their rigid state at room temperature. Top
THERMOSET
A plastic which, when cured by application of heat or chemical means, changes into a substantially infusible and insoluble material. Top
THIXOTROPIC, THIXOTROPY
Concerning materials that are gel-like at rest but fluid when agitated; having high static shear strength and low dynamic shear strength, at the same time. Top
TOLERANCE
The total amount by which a quantity is allowed to vary. Top
TOLERANCE LIMIT
A lower (upper) confidence limit on a specified percentile of a distribution. Top
TOOL
The mould, either one- or two-sided and either open or closed, in or upon which composite material is placed in order to make a part. Top
TOUGHNESS
Tendency of a material to absorb work. Top
TOW
An untwisted bundle of continuous filaments, usually designated by a number followed by "K", indicating multiplication by 1000; for example, 12K tow has 12,000 filaments. Top
TRANSLUCENT
Permits a percentage of light to pass but not optically clear like window glass. Top
TRANSVERSELY ISOTROPIC
Descriptive term for a material exhibiting a special case of orthotropy in which properties are identical in two orthotropic dimensions, but not the third; having identical properties in both transverse directions but not the longitudinal direction. Top
U
ULTIMATE TENSILE STRENGTH
The ultimate or final stress sustained by a specimen in a tension test; the stress at moment of rupture. Top
UNIDIRECTIONAL
Refers to fibres that are oriented in the same direction, such as unidirectional fabric, tape, or laminate, often called UD. Top
UV STABILIZER
A chemical compound which improves resistance to degradation from ultraviolet radiation. Top
V
VACUUM BAG MOULDING
A moulding technique in which the part is cured inside a layer of film, from which entrapped air is removed by vacuum. Top
VAPOR BARRIER
A material through which water vapour will not pass readily or at all. Top
VEIL
An ultra thin mat similar to a surface mat, often composed of organic fibres as well as glass fibres. Top
VISCOSITY
The property of resistance to flow exhibited within the body of a material, expressed in terms of relationship between applied shearing stress and resulting rate of strain in shear. Viscosity is usually taken to mean Newtonian viscosity, in which case the ratio of shearing stress to the rate of shearing strain is constant. In non-Newtonian behaviour, which is the usual case with plastics, the ratio varies with the shearing stress. Such ratios are often called the "apparent viscosities" at the corresponding shearing stresses. Top
VOID CONTENT
The percentage of voids in a laminate. Top
VOID FREE
A laminate containing no entrapped air cavities, blisters, or voids. Top
VOIDS
Pockets of entrapped gases that have not been cured into a laminate. Top
VOLATILE ORGANIC COMPOUNDS (VOC)
Carbon-containing chemical compounds (e.g., solvents or liquids) that evaporate readily at ambient or process temperatures. Environmental, safety and health regulations often limit exposure to these compounds, making low VOC content is preferable. Top
VOLATILE PORTIONS
Those portions vaporizing under specific conditions short of decomposition. Non-volatiles remain. Top
VOLATILES
Materials in a sizing or a matrix formulation that can be vaporized at room or slightly elevated temperature. Top
W
WARP
The yarns running lengthwise and parallel to the selvage in a woven fabric. Top
WARPAGE
Dimensional distortion in a composite part. Top
WATER ABSORPTION
Ratio of weight of water absorbed by a material to the weight of dry material. Also called moisture content. Top
WATER JET
A high-pressure stream of water used for cutting organic composites. Top
WAX
A mould release agent. Top
WEAVE
The particular manner in which a fabric is formed by interlacing yarns, and usually assigned a style number. Top
WEFT
The yarns running perpendicular to the warp in a woven fabric; also called "woof". Top
WET-OUT
The condition of an impregnated roving or yarn wherein substantially all voids between the sized strands and filaments are filled with matrix. Top
WET-OUT RATE
The time required for a plastic to fill the interstices of a reinforcement material and wet the surface of the reinforcement fibres; usually determined by optical or light transmission means. Top
WET-THRU
Where the matrix flows between the glass bundles or flows through the interstices of the woven roving or fabric. Top
WIND ANGLE
The measure in degrees between the direction parallel to the filaments and an established reference point. Top
WINDING PATTERN
The regularly recurring pattern of the filament winding after a certain number of mandrel revolutions. Top
WOVEN ROVING
A heavy glass fibre fabric made by the weaving of roving. Top
WOVEN ROVING FABRIC
Heavy fabrics woven from continuous filament in roving form. They drape well, are quickly impregnated, and intermediate in price between mats and yarn cloths. Top
WOVEN TAPE
Tape of various thicknesses woven from continuous filament yarns. Top
WRINKLE
An imperfection in the surface of a laminate that looks like a crease in one of the outer layers; it occurs in a vacuum bag moulding due to improper placement of the bag. Top
X
X-AXIS
The axis in the plane of the laminate used as reference. Top
X-Y PLANE
In composite laminates, the reference plane parallel to the plane of the laminate. Top
Y
Y-AXIS
The axis in the plane of the laminate perpendicular to the X-axis. Top
YARN
Short for Hybrid Yarn. Hybrid yarn or continuous fibres or strands suitable for use in fabrics. Top
YIELD STRENGTH
The stress at which a material exhibits a specified limiting deviation from the proportionality of stress to strain; the lowest stress at which a material undergoes plastic deformation. Below this stress, the material is elastic; above it, viscous. Top
YOUNG'S MODULUS
The ratio of tensile stress to tensile strain below the proportional limit. Top
Z
Z-AXIS
The reference axis normal to the laminate plane in composite laminates. Top