Definitions /Dictionary/Glossary - nptel

Fiber System: The type and arrangement of fibrous material which comprises the fiber
constituent of an advanced composite. Examples of fiber systems are collimated filaments or
filament yarns, woven fabric, randomly oriented short-fiber ribbons, random fiber mats,
whiskers, etc.
Fiber Volume (Fraction): See fiber content.
Filament: The smallest unit of a fibrous material. The basic units formed during spinning and
which are gathered into strands of fiber, (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.
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 numbers of layers
are applied the wound form is cured and the mandrel removed.
Filaments: Individual glass fibers 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.
Filament Yarn: A yarn composed of continuous filaments assembled with or without twists.
Filamentary Composite: A composite material reinforced with continuous fibers. It is a major
form of advanced composites in which the fiber constituent consists of continuous filaments.
Specifically, a filamentary composite is a laminate comprised of a number of laminae, each of
which consists of a nonwoven, parallel, uniaxial, planar array of filaments (or filament yarns)
embedded in the selected matrix material. Individual laminae are directionally oriented and
combined into specific multiaxial laminates for application to specific envelopes of strength and
stiffness requirements.
Filament winding: See Winding.
Filament Wound: Pertaining to an object created by the filament winding method of fabrication.
Fill (Filling): In a woven fabric, the yarn running from selvage to selvage at right angles to the
warp.
Filler: A relatively inert substance added to a material to alter its physical, mechanical, thermal,
electrical, and other properties or to lower cost. Sometimes the term is used specifically to mean
particulate additives.
Fill Threads: Also known as the weft. These are the crosswise fibers woven at 90 degrees to the
warp fibers.