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Composites Terminology Database

This glossary is not an exhaustive list, however it does contain the majority of terms used in the composites industry and as part of the management of our website, it is updated on a continual basis.

The terms are accessed by clicking on the appropriate letter below, all the terms beginning with the letter U can be found below.

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Terms U

Click on a term and it will take you to the coresponding explanation.

ultimate elongation
The elongation at rupture.

ultimate tensile strength
The ultimate or final (highest) stress sustained by a specimen in a tension test. Rupture and ultimate stress may or may not be the same.

ultrasonic testing
A non-destructive test applied to materials for the purpose of locating internal flaws or structural discontinuities by the use of high-frequency reflection or attenuation (ultrasonic beam).

Zone of invisible radiations beyond the violet end of the spectrum of visible radiations. Since UV wavelengths are shorter than visible wavelengths, their photons have more energy, enough to initiate some chemical reactions and to degrade most plastics, particularly aramids.

An area within a bonded interface between two adherents in which the intended bonding action failed to take place, or where two layers of prepreg in a cured component do not adhere to each other. Also used to denote specific areas deliberately prevented from bonding in order to simulate a defective bond, such as in the generation of quality standards specimens.

A condition of the moulded article resulting from the allowance of too little time and/or temperature or pressure for adequate hardening of the moulding.

uniaxial load
A condition whereby a material is stressed in only one direction along the axis or centreline of component parts.

unidirectional laminate
A reinforced plastic laminate in which substantially all of the fibres are oriented in the same direction.

unsaturated compounds
Any compound having more than one bond between two adjacent atoms, usually carbon atoms, and capable of adding other atoms at that point to reduce it to a single bond.

unsymmetric laminate
A laminate having an arbitrary stacking sequence without midplane symmetry.

urethane plastics
Plastics based on resins made by condensation of organic isocyanates with compounds or resins that contain hydroxyl groups. The resin is furnished as two component liquid monomers or prepolymers that are mixed in the field immediately before application. A great variety of materials are available, depending upon the monomers used in the prepolymers, polyols, and the type of diisocyanate employed. Extremely abrasion and impact resistant.
"isocyanate plastics" "polyurethane"

See ultraviolet

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