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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 E can be found below.

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Terms E

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

A family of glasses with a calcium aluminoborosilicate composition and a maximum alkali content of 2.0%. A general purpose fibre that is most often used in reinforced plastics and is suitable for electrical laminates because of its high resistivity. Also called electric glass. See

E1 is the modulus of elasticity in the direction of the fibres in a unidirectionally reinforced composite.

Modulus of elasticity in the direction perpendicular to the fibre orientation of a unidirectionally reinforced composite.

edge distance ratio
The distance from the centre of the bearing hole to the edge of the specimen in the direction of the principal stress, divided by the diameter of the hole.

edge joint
A joint made by bonding the edge faces of two adherents.

elastic deformation
The part of the total strain in a stressed body that disappears upon removal of the stress.

elastic limit
The greatest stress a material is capable of sustaining without permanent strain remaining after the complete release of the stress. A material is said to have passed its elastic limit when the load is sufficient to initiate plastic, or non-recoverable, deformation.

elastic recovery
The fraction of a given deformation that behaves elastically. A perfectly elastic material has an elastic recovery of l; a perfectly plastic material has an elastic recovery of 0.

That property of materials by virtue of which they tend to recover their original size and shape after removal of a force causing deformation. See: viscoelasticity.

A material that substantially recovers its original shape and size at room temperature after removal of a deforming force.

elastomeric tooling
A tooling system that uses the thermal expansion of rubber materials to form composite parts during cure.

electrical dissipation factor
The ratio of the power loss in a dielectric material to the total power transmitted through it; thus, the imperfection of the dielectric. Equal to the tangent of the loss angle.

electroformed moulds
A mould made by electroplating metal on the reverse pattern of the cavity. Molten steel may then be sprayed on the back of the mould to increase its strength.

elongation at break
Elongation recorded at the moment of rupture of the specimen, often expressed as a percentage of the original length.

Deformation caused by stretching. The fractional increase in length of a material stressed in tension. (When expressed as percentage of the original gage length, it is called percentage elongation.)

The enclosure of an item in plastic. Sometimes used specifically in reference to the enclosure of capacitors or circuit board modules.

end count
An exact number of ends supplied on a ball of roving.

A strand of roving consisting of a given number of filaments gathered together. The group of filaments is considered an end (or strand) before twisting, a ''yarn'' after twist has been applied. An individual warp yarn, thread, fibre, or roving.

endurance limit
See: fatigue limit

The aggregate of all conditions (such as contamination, temperature, humidity, radiation, magnetic and electric fields, shock, and vibration) that externally influence the performance of an item.

environmental stress cracking (ESC)
The susceptibility of a thermoplastic resin to crack or craze when in the presence of surface active agents or other environments.

The basic epoxidising resin intermediate in the production of epoxy resins. It contains an epoxy group and is highly reactive with polyhydric phenols such as bisphenol A.

Compound containing the oxirane structure, a three-member ring containing two carbon atoms and one oxygen atom. The most important members are ethylene oxide and propylene oxide.

epoxy plastic
A polymerisable thermoset polymer containing one or more epoxide groups and curable by reaction with amines, alcohols, phenols, carboxylic acids, acid anhydrides, and mercaptans. An important matrix resin in composites and structural adhesive.

In filament winding, the line in a pressure vessel described by the junction of the cylindrical portion and the end dome. Also called tangent line or point.

See: environmental stress cracking

even tension
The process whereby each end of roving is kept in the same degree of tension as the other ends making up that ball of roving. See also catenary

The liberation or evolution of heat during the curing of a plastic product.

To add fillers or low-cost materials in an economy producing endeavour. To add inert materials to improve void-filling characteristics and reduce crazing.

Low-cost materials used to dilute or extend high-cost resins without extensive lessening of properties. See also filler

The ability of a material to extend or elongate upon application of sufficient force, expressed as percent of the original length.

extensional-bending coupling
A property of certain classes of laminates that exhibit bending curvatures when subjected to extensional loading.

extensional-shear coupling
A property of certain classes of laminates that exhibit shear strains when subjected to extensional loading.

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