Definitions /Dictionary/Glossary - nptel

Young's Modulus: The ratio of tensile stress to tensile strain below the proportional limit.
Yield Strength: The stress at which a material exhibits a specified limiting deviation from the
proportionality of stress to strain. (The deviation is expressed in terms of strain such as 0.2
percent for the Offset Method or 0.5 percent for the Total Extension under Load Method.)
Z-Axis: In composite laminates, the reference axis normal to the plane of the laminate.
Zero Bleed: Laminate fabrication procedure that does not allow loss of resin during cure.
(From) http://www.composites-by-design.com/glossary.htm
A-stage: An early stage of polymerization of thermosetting resins in which the material is still
soluble in certain liquids and is fusible. It is also called resole. See also B-stage and C-stage.
Ablative: A material that absorbs heat through a decomposition process called pyrolysis at or
near the exposed surface.
Addition: A polymerization reaction in which no by-products are formed.
Additives: Ingredients mixed into resin to improve properties.
Adhesive failure: A rupture of adhesive bond that appears to be a separation at the adhesiveadherend
interface.
Amorphous: Polymers that have no order to their molecules, thus no crystalline component.
Anisotropic: The tendency of a material to exhibit different properties in response to stresses
applied along axes in different directions.
Aramid: Aromatic polyamide fibers characterized by excellent high-temperature, flameresistance,
and electrical properties. Aramid fibers are used to achieve high-strength, highmodulus
reinforcement in plastic composites.
Arial weight: The weight of fiber per unit area (width time’s length) of tape or fabric.
Aspect ratio: The ratio of length to diameter of a fiber.
Autoclave: A closed vessel that permits application of pressure and heat used for curing
composites.