Definitions /Dictionary/Glossary - nptel

Lightning Strike Zones: Aircraft surface areas and structures classified according to the
possibility of lightning attachment dwell time and current conduction.
Linear Expansion: The increase of a given dimension, measured by the expansion or
contraction of a specimen subject to a thermal gradient or changing temperature.
Liner: In a filament wound pressure vessel, the continuous coating on the inside .surface of the
vessel, used to protect the laminate from chemical attack or to prevent leakage under stress.
Liquid Adhesive: An adhesive that is in the liquid state when applied.
Liquid-Crystal Polymers: A newer type of thermoplastic, melt processible, with high
orientation in molding, improved tensile strength, and high-temperature capability.
Load-Deflection Curve: A curve in which the increasing flexural loads are plotted on the
ordinate axis and the deflections caused by those loads are plotted on the abcissae axis.
Loft: The height of the glass lay-down either dry (as in chopping SMC glass) or wet (as in the
height of the glass/resin mixture in a spray-up on the mold before roll-out).
Lognormal Distribution: A probability distribution for which the probability that an
observation selected at random from this population falls between ‘a’ and ‘b’ (0 < a < b < B) is
given by the area under the normal distribution between log ‘a’ and ‘log b’. The common (base
10) or the natural (base e) logarithm may be used.
Loss on Ignition: Weight loss, usually expressed as percent of total, after burning off an organic
sizing from glass fibers, or an organic resin from a glass fiber laminate.
Lower Confidence Bound: See Confidence Interval.
Low Profile Additives: Low profile additives are thermoplastics that are added to the
formulation in 2-5% (by weight) of the final product to control the shrinkage of the cured
composites.
Low Profile: Low shrink resins, which reduce surface distortion.
Low-Pressure Laminants: In general, laminates molded and cured in the range of pressures
from 400 psi down to an including pressure obtained by the mere contact of the plies.
Low-Pressure Molding: The distribution of relatively uniform low pressure (200 psi or less)
over a resin-bearing fibrous assembly of cellulose, glass, asbestos, or other material, with or
without application of heat from external source, to form a structure possessing definite physical
properties.
LPF: Last Ply Failure.