Definitions /Dictionary/Glossary - nptel

Diluent: Diluting (reducing or thinning) agent.
Dimensional Stability: Capability of an item to maintain its constructed dimensions without
distorting.
Dimethyl Aniline (DMA): Accelerator used in conjunction with BPO catalyst. It is more
effective than DEA.
Dimples: Small sunken dots in the gel coat surface, generally caused by a foreign particle in the
laminate.
Direct Wound 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 centers and no
Catenary.
Disbond: An area within a bonded interface between two adherents in which an adhesion failure
or separation has occurred. It may occur at any time during the life of the structure and may arise
from a wide variety of causes. Also, colloquially, an area of separation between two laminae in
the finished laminate (in this case the term "delamination" is normally preferred.) (See Debond,
Unbond, Delamination.)
Discontinuous Fibre Reinforced Composite: A ceramic-matrix composite material I reinforced
by chopped fibres.
Dispersion: The means of incorporating pigments into polyester.
Displacement Angle: -In filament winding, the advancement distance of the winding ribbon
after one complete circuit.
Distortion: A wavy gel coat image often found in conjunction with print through. It is
commonly caused by a problem in the laminating system.
Distribution: A formula which gives the probability that a value will fall within prescribed
limits (See Normal, Weibull, and Lognormal Distributions).
Doctor Roll; Doctor Bar: A device for regulating the amount of liquid material on the rollers of
a spreader.
Dolly: In filament winding, the planar reinforcement applied to a local area between windings to
provide extra strength in an area where a cut-out is to be made.
Dome: In filament winding, the portion of a cylindrical container that forms the spherical or
elliptical shell.