Definitions /Dictionary/Glossary - nptel

Micro-balloons: Microscopic bubbles of glass, ceramic or Phenolic, used as a filler or to create
syntactic foam or putty mixtures.
Microcracking: Microscopic cracks formed in composites when thermal stresses locally exceed
the strength of the matrix.
Micro-mechanics: Analysis of the structural behaviour of composites on a constituent (matrix,
reinforcement, interface) level.
Micron: One micron = .001 millimeter = .00003937 inch.
Microspheres: Microscopic bubbles of glass, ceramic or phenolic, used as a filler or to create
syntactic foam or putty mixtures.
Micro-strain: The strain over a gage length comparable to the material's inter-atomic distance.
Microstructure: A structure with heterogeneities that can be seen through a microscope.
Mil: The unit used in measuring film thickness and the diameter of glass fiber strands, wire, etc.
(one mil = .001")
Mil Thickness: Mils - The unit used in measuring film thickness. One mil equals one
thousandth of an inch. (1mil = .001).
Milled Fibers: Crushed glass used generally for making glass filled putty.
Modulus: A number which expresses a measure of some property of a material: modulus of
elasticity, shear modulus, etc.; a coefficient of numerical measurement of a property. (Note: The
use of the word without modifying terms may be confusing; and such use should not be
encouraged.)
Modulus, Chord: The slope of the chord drawn between any two specified points on the stressstrain
curve.
Modulus, initial: The slope of the initial straight portion of a stress-strain curve.
Modulus of Elasticity: The ratio of the stress or load applied to the strain or deformation
produced in a material that is elastically deformed. If a tensile strength of 2000 pounds per
square inch results in an elongation of one percent, the modulus of elasticity is 2000 divided by
0.01, or 200,000 pounds per square inch (Young's Modulus).
Modulus, Secant: The slope of the secant drawn from the origin to any specified point on the
stress-strain curve.