Definitions /Dictionary/Glossary - nptel

X axis: The axis in the plane of the laminate used as 0 degree reference; the Y axis is the axis in
the plane of the laminate perpendicular to the X axis; the Z axis is the reference axis normal to
the laminate plane in composite laminates.
Yarn: Continuously twisted fibers or strands suitable for use in weaving into fabrics.
Young's modulus: The ratio of normal stress to the corresponding strain for tensile or
compressive stresses less than the proportional limit of the material.
Source: Information herein was obtained from various government agencies. None of the text
within this section is copyrighted material to the best knowledge of Composites-By-Design.
ABS: Acrylonitrile Butadiene Styrene (Thermoplastic Resin).
Ablative Plastic: A material that absorbs heat (with low material loss and char rate) through a
decomposition process (pyrolysis). Absorption takes place at or near the surface exposed to the
heat.
Abrasion: Wearing away by friction. Glass is highly resistant to abrasion from other materials,
but can be damaged through contact with itself. Lubrication during processing and fabrication
helps prevent abrasion.
Accelerated Test: Procedure in which conditions are magnified to reduce the time required to
obtain a result, or to reproduce the deteriorating effects of normal service conditions in a very
short time period.
Accelerator (Promoter): A highly active oxidizing agent used to speed up the chemical reaction
(curing) between a catalyst and resin. Examples include diethylaniline, cobalt naphthanate and
cobalt octoate.
Activator: See Accelerator.
Acoustic Emission: The amount of integrity in a material after it has been stressed, as
determined by sound emission. Ideally, emissions can be correlated with defects and/or early
failure.
Acrylic: Thermoplastic polymer made by the polymerization of esters of acrylic acid and its
derivatives.
Actual End Count: The number of bundles or splits that are actually counted in one doff of
roving. (This is less than the theoretical end count due to splitting efficiencies of less than
100%).