Technical data

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E. Terminology
The following terms are used throughout this Chapter. Technicians involved in composite repair should
be familiar with the following definitions, the materials used, and the procedures required.
Backing Plate A plate used behind a hole in the structure when making a composite repair. The backing
plate is considered a tool and is not considered to add any strength to the repair.
Core The central member, usually foam or honeycomb, of a sandwich construction to which the
laminate faces of the sandwich are attached or bonded.
Delamination Separation of the core and laminate face sheets or separation between plies of a laminate.
Disbond An area within a bonded interface between two parts in which an adhesion failure or separa-
tion has occurred.
Fiber Direction The orientation or alignment of the longitudinal axis of the fiber with respect to a stated refer-
ence axis.
Filler A relatively inert substance added to a material to alter its physical, mechanical, thermal,
electrical, and other properties. Fillers are also used to lower cost and density.
Glass Cloth A type of fabric made from fine spun glass filaments which are woven into a strong, tough
fabric. These fabrics are used to construct, reinforce, and repair composite structures.
Glass Fiber Filaments of fine spun glass.
Initial-cure Minimum cure cycle required to achieve handling strength. Required before the laminate or
repair is handled, processed, or stressed in any way.
Lamince Single layer of unidirectional or woven fibers embedded in a resin matrix.
Laminate To unit laminae, usually with heat and pressure. A product made by such bonding.
Peel Ply A special ply used as the outer layer which is peeled off after cure to provide a smooth con-
taminate free repair surface.
Plies Layers of material (glass cloth or glass fiber) which are laminated together.
Post-cure Additional elevated-temperature cure, usually without pressure, to improve final properties
and/or complete the cure. In certain resins, complete cure and ultimate mechanical proper-
ties are attained only by exposure of the cured resin to higher temperature than those of ini-
tial curing.
Release Film An impermeable layer of film that does not bond to the resin being cured. Both sides of the
release film are adhesive free.
Release Tape A plastic film with adhesive backing on one side. Release tape is used during backing plate
manufacture to allow the backing plate to release from the lay-up surface without damage.
Sandwich Con-
struction
A bonded structure in which a core of material such as rigid foam is bonded between two
laminate face sheets of metal or fiberglass cloth. Sandwich constructed materials are used
where high strength and light weight are required.
Scarf Joint A joint made by cutting away angular segments of a part and then either bonding a second
part with similar angular cuts or wet laying material with staggered widths.
Template A pattern made of any suitable material to permit the layout of parts with a minimum expen-
diture of time and effort.