Definitions /Dictionary/Glossary - nptel

Puckers: Local areas on prepreg where material has blistered and pulled away from the
separator film or release paper.
Puncture: Break in composite skin in sandwich structure that may or may not go through to the
core material or completely through the part.
Pultrusion: Reversed "extrusion" of resin-impregnated roving in the manufacture of rods, tubes
and structural shapes of a permanent cross-section. The roving, after passing through the resin
dip tank, is drawn through a die to form the desired cross-section.
Putty: A thickened mixture of resin made by adding fillers, thixotrophs and reinforcing fibers.
Quasi-Isotropic Laminate: A balanced and symmetric laminate for which a
constitutive property of interest, at a given point, displays isotropic behavior in the plane of the
laminate.
Discussion: Common quasi-isotropic laminates are [ 0/ ± 60] and[ 0/ ± 45/60] .
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Ramping: A gradual, programmed increase/decrease in temperature or pressure to control
the cure or cooling of composite parts.
Random Effect: A shift in a measured quantity due to a particular level change of an external,
usually uncontrollable, factor.
Random Error: That part of the data variation that is due to unknown or uncontrolled factors
and that affects each observation independently and unpredictably.
Rate Tools: Tools designed to be used repeatedly in a production
Reduction of Area: The difference between the original cross sectional area of a tension test
specimen and the area of its smallest cross section, usually expressed as a percentage of the
original area.
Refractive Index: The ratio of the velocity of light (of specified wavelength) in air to its
velocity in the substance under examination. It is also defined as the sine of the angle of
incidence divided by the sine of the angle of refraction as light passes from air into the substance.
Reinforced Molding Compound: Compound supplied by raw material producer in the form of
ready-to-use material, as distinguished from premix.
Reinforced Plastic: A plastic with relatively high stiffness or very high strength fibers
embedded in the composition. This improves some mechanical properties over that of the base
resin.
Reinforcement: A strong inert material bonded into a plastic to improve its strength, stiffness,
and impact resistance. Reinforcements are usually long fibers of glass, asbestos, sisal, cotton,