Glossary

Glossary of composites related terms beginning with the letter D

Damage tolerance

A measure of a structure's ability to retain load-carrying capability after exposure to sudden loads (for example, ballistic impact).

Damping

Diminishing the intensity of vibrations.

Debond

Deliberate separation of a bonded joint or interface, usually for repair or rework purposes. (See also disbond.)

Delamination

Separation of plies in a laminate due to adhesive failure. This may occur locally or involve a large area. Also includes the separation of layers of fabric from the core structure.

Demold

To remove a part from a tool or a tool from an intermediate model.

Denier

Numbering system for continuous yarn and continuous filaments in which the yarn number is equal to the weight in grams per 9,000 meters of yarn; the finer the yarn, the lower the denier.

Design allowable

A limiting value for a material property that can be used to design a structural or mechanical system to a specified level of performance with a specific level of statistical confidence.

Dielectric

Electrically nonconductive; the ability of a material to resist the flow of an electric current.

Dielectric strength

The voltage required to penetrate insulating material. Material with high dielectric strength offers excellent electrical insulating properties.

Disbond

Undesirable separation of bonded surfaces at the bond interface, due to adhesive or cohesive failure, occurring at any time during the life of the bonded structure and arising from any of a wide variety of causes. The term is also sometimes used to describe delamination. (Also see debond.)

Doubler

An extra layer of reinforcement, applied to increase stiffness or strength in portions of a laminate expected to incur abrupt load transfers.

Draft

The degree of taper designed into the sides of a mold so the part can be removed.

Draft angle

A mandrel's taper or angle for ease of part removal.

Drape

The ability of fabric or prepreg to conform to a contoured surface.

Dry winding

In filament winding, when fiber reinforcement is applied to the mandrel without first being wet out with resin.