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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 N can be found below.

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Terms N

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

See non-destructive evaluation
"non-destructive evaluation"

See non-destructive inspection
"non-destructive inspection"

See non-destructive testing
"non-destructive testing"

neat resin
Resin to which nothing (additives, reinforcements, and so on) has been added.

The localised reduction in cross section that may occur in a material under tensile stress.

needled mat
A mat formed of strands cut to 3 short length, then felted together in 3 needle loom, with or without a carrier.

In reinforced plastics, the placing of plies of fabric so that the yarns of one ply lie in the valleys between the yarns of the adjacent ply (nested cloth).

netting analysis
The analysis of filament wound structures that assumes the stresses induced in the structure are carried entirely by the filaments, and the strength of the resin is neglected; assumes also that the filaments possess no bending or shearing stiffness; carry only the axial tensile loads.

The connected portion of adjacent ribbons of honeycomb.

NOL ring
A parallel filament- or tape-wound hoop test specimen developed by the Naval Ordnance Laboratory (NOL), (now the Naval Surface Weapons Laboratory), for measuring various mechanical strength properties of the material, such as tension and compression, by testing the entire ring or segments of it. Also known as a parallel fibre reinforced ring.

nominal stress
The stress at a point calculated on the net cross section without taking into consideration the effect on stress of geometric discontinuities, such as holes, grooves, fillets, and so forth. The calculation is made by simple elastic theory.

nominal value
A value assigned for the purpose of a convenient designation. A nominal value exists in name only. It is often an average number with a tolerance so as to fit together with adjacent parts.

non-destructive evaluation (NDE)
Broadly considered synonymous with non-destructive inspection (NDI). More specifically, the analysis of NDI findings to determine whether the material will be acceptable for its function.

non-destructive inspection (NDI)
A process or procedure, such as ultrasonic or radiographic inspection, for determining the quality or characteristics of a material, part, or assembly, without permanently altering the subject or its properties. Used to find internal anomalies in a structure without degrading its properties.

non-destructive testing (NDT)
Broadly considered synonymous with non-destructive inspection (NDI).

Lacking the property of absorbing and retaining an appreciable quantity of moisture (water vapour) from the air.

non-woven fabric
A planar textile structure produced by loosely compressing together fibres, yarns, rovings, and so forth, with or without a scrim cloth carrier. Accomplished by mechanical, chemical, thermal, or solvent means and combinations thereof.

normal stress
The stress component that is perpendicular to the plane on which the forces act.

notch factor
Ratio of the resilience determined on a plain specimen to the resilience determined on a notched specimen.

notch sensitivity
The extent to which the sensitivity of a material to fracture is increased by the presence of a surface non-homogeneity, such as a notch, a sudden change in section, a crack, or a scratch. Low notch sensitivity is usually associated with ductile materials, and high notch sensitivity is usually associated with brittle materials.

notched specimen
A test specimen that has been deliberately cut or notched, usually in a V-shape, to induce and locate point of failure.

A linear thermoplastic B-staged phenolic resin, which, in the presence of methylene or other cross-linking groups, reacts to form a thermoset phenolic.

Poisson's ratio. See Poisson's ratio
"Poisson's ratio"

nylon plastics
uln a laminate, the contact area between the reinforcement and the laminating resin.

The generic name for all synthetic polyamides.

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