Twill weave

The simplest weave style, in which each warp yarn passes alternately over and under each weft yarn. It is stable and easy to handle but has the highest crimp of the common weave styles, which slightly reduces mechanical performance and limits drape over complex curvature.

A low crimp weave style in which each warp yarn floats over several weft yarns before interlacing, described by its harness number, for example four harness or eight harness satin. It offers excellent drape and surface smoothness at the cost of a less stable, asymmetric fabric that requires care in handling and lay up.

The two yarn directions in a woven fabric, with warp yarns running along the roll length and weft yarns running across it. Their balance governs the directional properties of the fabric, and the terms ends and picks describe the respective yarn counts.

A reinforcement fibre produced by carbonising a precursor, most commonly polyacrylonitrile (PAN) or pitch, to give continuous filaments composed largely of carbon. It offers very high stiffness and strength for its weight and is the principal reinforcement in high performance composites. Grades are commonly described by modulus class, such as standard, intermediate and high modulus.