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ME-542 Manufacturing with Non-metallic MaterialsA list of ME 542-relevant definitions
Index
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Autoclave: A closed vessel that applies pressure to objects inside such as bagged laminates.
B-stage: A partially cured resin or prepreg product
Bagging: the process of applying an impermeable layer of film over a part and sealing the edges so that a vacuum can be drawn. The bag permits a pressure differential to exist between the pressurizing medium and the part.
Balanced laminate: A composite laminate in which all laminae at angles other than 0° and 90° occur in pairs.
Barrier film: The layer of film used to remove volitiles from a curing laminate while limiting resin loss.
Bleeder cloth: Material , like fiberglass cloth, that allows both volitiles and resin to escape from a laminate during cure.
Breather cloth: Material used to support the presence of a vacuum above the laminate and thereby create a pressure differential.
Catalyst: A chemical which promotes a chemical reaction without becoming part of the molecular structure of the product. In polymers, catalysts lower the temperature a which a reaction of a given rate can occur.
Coefficient of thermal expansion: The dimensional change of an object with temperature is measured in microinches/inch/°C. Graphite has a negative axial CTE.
Compression Molding: The process of placing a polymer or elastomer into a mold cavity, closing the mold, and applying pressure and heat to make the material fill the mold and, when applicable, to cure.
Consolidation: Diffusion bonding of metal-matrix or thermoplastic composite laminae into a laminate.
Cross-linking: Chemical reaction that results in a branched network of molecules.
Cross-ply: A laminate with plies in different directions. Fabrics don't automatically belong to this group.
Crystallinity: Thermoplastic polymers often form regions of high molecular order - crystalinity - that have superior mechanical properties.
Cure: The irreversible chemical change that occurs in a thermosetting polymer during processing.
Curing Cycle: The time/temperature/pressure cycle used to cure a thermosetting composite.
Cure stress: Internal stresses which may or may not result in significant external strains and that result from the effects of CTE and lay-up sequences.
Dam: Edge support used to prevent excessive edge bleed or crowning of bag.
Delamination: The separation of layers of a laminate from one another.
Drape: The ability of a preform to conform to a contoured surface,
Envelope Bag - A vacuum bag that encloses both the part and the tool.
Fiber Content: The amount of fiber or other single filler present usually expressed as a volume fraction or weight fraction of the specimen as a whole.
Fiber Direction: Orientation of the fiber axis of a ply relative to a stated reference direction.
Fiber Finish: A material applied to the surface of a fiber to alter its bond with the matrix.
Fiber Tow: A loose, untwisted, collimated bundle of continuous fibers.
Flash: Excess resin that forms at the parting line of a mold of die.
Gel Temperature: The temperature at which the viscosity of a thermosetting resin becomes so high that no further flow can be induced. This temperature is influenced by the entire cure history.
Gel Time: Time required for a resin to reach gel condition at a standard constant temperature.
Gelcoat: A hard dense resin applied to a mold surface before the structural layers.
Glass Transition Temperature: The inflection point on a modulus vs. temperature plot at which properties significantly decrease.
Hand-layup: A process in which composite components are assembled from laminar materials by hand against a mold or tool.
Harness Satin: Describes a set of weaving patterns used to produce different satin fabrics. Satins of 4 and 8 harness are common.
Hot melt process: method of producing impregnated fiber forms using heat and pressure to press thin films of resin into porous filamentary preforms.
Hybrid: A composite laminate containing two or more different reinforcement or resin systems.
Inclusion: A geometric or mechanical discontinuity occurring in a material or structure usually consisting of a solid foreign body.
Interface: The intermediate region between fiber and matrix in a composite.
Interply: Between separate plies
Intraply: Within a single ply.
Lamina: A single ply or layer of composite preform.
Laminae: Plural of lamina.
Laminate: A product made by bonding lamina together usually under the action of heat and pressure
Layup: The process of lamination or the laminate itself.
Mat: A randomly oriented collection of long, swirled reinforcing fibers held together with a binder resin.
Matched Die: A multi-piece mold capable of producing two or more dimensionally controlled surfaces in a part.
Matrix: The macroscopically homogeneous phase of a composite material.
Microcracking: Matrix cracks that usually result from thermal residual stresses.
Moisture Content: The weight gain percent of a composite when exposed to saturated water vapor for extended periods.
Mold Release: A lubricant designed to fill mold pores and facilitate removal of the part from the mold.
NDI: Non-destructive Inspection usually via ultrasonic means.
Orthotropic: Possessing three mutually perpendicular planes of elastic symmetry.
Out Time: The cumulative period that prepreg is out of the freezer.
Peel-ply: A layer of thin open-weave material applied to the laminate surface during cure and removed by peeling just before bonding or painting.
Plain weave: A weave pattern where the warp and fill fibers alternate.
Plastic: Generic term for a mixture of polymer and ingredients such as fillers, hardeners, etc.
Plasticizer: A low molecular weight material added to a polymer to separate the polymer chains and improve flow.
Ply: A synonym for lamina
Polymerization: Conversion of monomer to polymer
Porosity: Regions of air, gas, or voids in a plastic or a composite laminate and usually expressed as a volume percentage
Postcure: Use of an oven for completion of thermosetting cure.
Pot Life: The time available to work with a thermosetting polymer after addition of a catalyst before gel occurs.
Prepreg: Ready to use, reinforced composite preform that is usually pre-staged.
Pressure Intensifier: A shop aid, usually a layer of flexible material, used to ensure extra pressure in a particular region of the composite part.
Quasi-isotropic: A layup with equal amounts of plies in each of the following directions: 0°, +45°, -45°, 90° only.
Reinforcement: A relatively high strength or stiffness material embedded in a lower performance matrix material.
Release Film: An impermeable film which does not bond to the resin being used.
Secondary Bonding: Adhesive bonding of two or more previously cured components into an assembly.
Symmetrical Laminate: A composite laminate in which the ply orientation is symmetric about the midplane.
Tape: Prepreg consisting of unidirectional reinforcing fibers and resin supported by a layer of release paper or film. Graphite tape is usually about 0.005 inch thick.
Thermoforming: Using heat to soften a thermoplastic and thereby permit controlled deformation.
Thermoplastic: A plastic that can be cyclically softened and hardened by raising and lowering the temperature and that can be molded while soft.
Thermoset: A plastic that undergoes a permanent chemical change to become infusible and insoluble after cure.
Vacuum Bag: A impermeable plastic, foil or rubber layer used to cover the part so that vacuum an be drawn.
Vacuum Bag Molding: A process in which heat and a pressure differential produced from evacuation of a vacuum bagged laminate produces cure.
Vent Cloth: "Breather Cloth" Layers of open weave cloth used to propagate a vacuum condition over the entire laminate surface adjacent to the cloth.
Viscosity: The property of a liquid that relates applied stress to the velocity gradient it produces. "Resistance to flow"
Void: Planar or volumetric discontinuities in a composite laminate. Porosity is a group of voids.
Volatiles: Refers to vaporous materials leaving a laminate that is being cured. These include solvents, absorbed, water, and products of the cure reaction.
Warp: The longitudinally oriented yarn in a weave.
Weft: The transversely oriented yarns in a weave.
Wetout: The process of completely wetting a fiber bundle with a fluid resin.