Glossary

Glossary of composites related terms beginning with the letter L

Lamina

Subunit of a laminate consisting of one or more adjacent plies of the same material with identical orientation. (Plural: laminae.)

Lamina orientation

See ply orientation.

Laminate

To unite or bond two or more layers or laminae (often with the aid of pressure and/or heat). Any fiber- or fabric-reinforced composite consisting of laminae with one or more orientations with respect to some reference direction.

Laminate coordinate axes

Set of coordinate axes, usually right-handed Cartesian, used as a reference in describing the directional properties and geometrical structure of the laminate. Usually the x-axis and the y-axis lie in the plane of the laminate and the x-axis is the reference axis from which ply angle is measured. The x-axis is often in the principal load direction of the laminate and/or in the direction of the laminate principal axis. (See principal axis, off-axis laminate and x-axis.)

Lap joint

A joint made by overlapping two parts and bonding them together.

Layup

To place or the process of placing layers of reinforcing material into position in or on a mold; also used to refer to the reinforcing materials as placed in the mold ("the layup").

Layup code

Designation system for abbreviating the stacking sequence of laminated composites.

Liner

The continuous, usually flexible, reinforced resin barrier on the inside surface of a plastic or thermoset laminate, used to protect the laminate from chemical attack or to prevent leakage under stress.

Liquid-crystal polymers (LCP)

High-performance melt-processible thermoplastics that develop high orientation in the melt and after molding, resulting in very high tensile strength and high-temperature capability.

Lot

See batch.

Low profile

Describes resin compounds formulated for low-to-zero shrinkage during molding.