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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 T can be found below.

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Terms T

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

Extra lengths of composite or other material at the ends of a tensile specimen to promote failure away from the grips.

tack range
The period of time in which an adhesive will remain in the tacky-dry condition after application to the adherend, and under specified conditions of temperature and humidity.

Stickiness of an adhesive or filament reinforced resin prepreg material.

tangent modulus
The slope of the line at a predefined point on a static stress-strain curve, expressed in force per unit area per unit strain. This is the tangent modulus at that point in shear, tension, or compression, as the case may be. See also secant modulus.
"secant modulus"

tape wrapped
Fabric tape is heated and wrapped onto a rotating mandrel and subsequently cooled to firm the surface for the next tape layer application.

Unidirectional prepreg fabricated in widths up to 305 mm (12 in.) for carbon and 75 mm (3 in.) for boron. Woven broad goods carbon and glass tapes up to 1250 or 1500 mm (50 or 60 in.) wide are available commercially.

A pattern used as a guide for cutting and laying plies.

The term generally used in yarn manufacture and textile engineering to denote the strength of a yarn or of a filament of a given size. Numerically, it is the grams of breaking force per denier unit of yarn or filament size. Grams per denier is expressed as gpd.

tensile modulus
See Young's modulus.
"Young's modulus"

tensile strength, ultimate
See ultimate tensile strength
"ultimate tensile strength"

tensile strength
Maximum tensile strength in ksi.

tensile stress
The normal stress caused by forces directed away from the plane on which they act.

tenth-scale vessel
A filament wound material test vessel based on a one-tenth subscale of the prototype.

A polymeric system that contains three monomeric units.

A unit for expressing linear density equal to the mass or weight in grams of 1000 meters of filament, fibre, yarn, or other textile strand.

textile fibres
Fibres or filaments that can be processed into yarn or made into a fabric by interlacing in a variety of methods, including weaving, knitting, and braiding.

See glass transition temperature.

See thermogravimetric analysis
"thermogravimetric analysis"

thermal conductivity
Ability of a material to conduct heat. The physical constant for the quantity of heat that passes through a unit cube of a substance in unit time when the difference in temperature of two faces is 1 degree .

thermal endurance
The time at a selected temperature for a material or system of materials to deteriorate to some predetermined level of electrical, mechanical, or chemical performance under prescribed conditions of test.

thermal expansion moulding
A process in which elastomeric tooling details are constrained within a rigid frame to generate consolidation pressure by thermal expansion during the curing cycle of the autoclave moulding process.

thermal stress cracking
Crazing and cracking of some thermoplastic resins, resulting from overexposure to elevated temperatures. See also stress cracking.
"stress cracking"

Forming a thermoplastic material after heating it to the point where it is soft enough to be formed without cracking or breaking reinforcing fibres.

thermogravimetric analysis (TGA)
The study of the mass of a material under various conditions of temperature and pressure.

thermoplastic polyesters
A class of thermoplastic polymers in which the repeating units are joined by ester groups. The two important types are (1) polyethylene terephthalate (PET), which is widely used as film, fibre, and soda bottles; and (2) polybutylene terephthalate (PBT), primarily a moulding compound.

Capable of being repeatedly softened by an increase of temperature and hardened by a decrease in temperature. Applicable to those materials whose change upon heating is substantially physical rather than chemical and that in the softened stage can be shaped by flow into articles by moulding or extrusion.

A plastic that, when cured by application of heat or chemical means, changes into a substantially infusible and insoluble material.

thermosetting polyesters
A class of resins produced by dissolving unsaturated, generally linear, alkyd resins in a vinyl-type active monomer such as styrene, methyl styrene, or diallyl phthalate.

Cure is effected through vinyl polymerisation using peroside catalysts and promoters or heat to accelerate the reaction. The two important commercial types are (1) liquid resins that are cross-linked with styrene and used either as impregnants for glass or carbon fibre reinforcements in laminates, filament-wound structures, and other built-up constructions, or as binders for chopped-fibre reinforcements in moulding compounds, such as sheet moulding compound (SMC), bulk moulding compound (BMC), and thick moulding compound (TMC); and (2) liquid orÊsolid resins cross-linked with other esters in chopped-fibre and mineral-filled moulding compounds, for example, alkyd and diallyl phthalate.

thin-layer chromatography (TLC)
Makes a finished plastic more flexible or tough. See also plasticiser.

thixotropic (thixotropy)
Concerning materials that are gel-like at rest but fluid when agitated. Having high static shear strength and low dynamic shear strength at the same time. To lose viscosity under stress.

thread count
The number of yarns (threads) per inch in either the length wise (warp) or crosswise (fill or weft) direction of woven fabrics.

See fibre

See thin-layer chromatography
"thin-layer chromatography"

Maximum temperature in degrees F that part will be subjected to; sometimes called excursion temperature.

The guaranteed maximum deviation from the specified nominal value of a component characteristic at standard or stated environmental conditions.

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