Definitions /Dictionary/Glossary - nptel

Cycle: The complete, repeating sequence of operations in a process or part of a process. In
molding, the cycle time is the period (or elapsed time) between a certain point in one cycle and
the same point in the next.
D-Glass: A high boron content glass made especially for laminates requiring a precisely
controlled dielectric constant.
Dam: Boundary support used to prevent excessive edge bleeding or resin run out of a laminate
and to prevent crowning of the bag during cure.
Damage Tolerance: It is a measure of the ability of structures to retain load-carrying capability
after exposure to sudden loads (for example, ballistic impact).
Damping: Diminishing the intensity of vibrations.
Daylight: The distance in the open position, between the moving and fixed tables or the platens
of a hydraulic press. In the case of a multi-daylight press, daylight is the distance between
adjacent platens.
Debond: A deliberate separation of a bonded joint or interface, usually for repair or rework
purposes. See Disbond, Unbond.
Debulking: Compacting of a thick laminate under moderate heat and pressure and/or vacuum to
remove most of the air, vapour and volatiles between the plies.
Deep-Draw Mold: A mold having a core which is long in relation to the wall thickness.
Deflection Temperature under Load: The temperature at which a simple beam has deflected a
given amount under load (formerly called heat distortion temperature).
Deformation: The change in shape of a specimen caused by the application of a load or force.
Deformation Under Load: The dimensional change of a material under load for a specific time
following the instantaneous elastic deformation caused by the initial application of the load.
Also, see 'cold flow' or 'creep'.
Degassing: It is the opening and closing of a mold to allow gas to escape early in the molding
cycle. It is also called breathing.
Degradation: A deleterious change in chemical structure, physical properties or appearance.
Delamination: The separation of the layers of material in a laminate. This may be local or may
cover a large area of the laminate. It may occur at any time in the cure or subsequent life of the
laminate and may arise from a wide variety of causes.