Glossary of composite terms

A

Autoclave

An autoclave is a pressurised heated chamber in which a laminate under a vacuum bag cures under gas pressure at an elevated temperature.

B

Bladder (pressure bladder)

A bladder is a flexible bag filled with compressed gas that presses the laminate against the mould walls from the inside.

C

C-BMC

C-BMC (carbon bulk moulding compound) is a compound of chopped carbon fibre and resin, formed by compression or injection moulding.

C-SMC

C-SMC (carbon sheet moulding compound) is a semi-finished product in the form of sheets of chopped carbon fibre impregnated with resin, intended for hot compression moulding.

CFRP

CFRP (carbon fibre reinforced polymer) is a polymer composite reinforced with carbon fibre, commonly called “carbon”.

E

Expanding core

An expanding core is a heat-activated material that foams inside a closed mould, fills the inside of the part and presses the laminate against the mould walls from within.

F

Fibre orientation

Fibre orientation is the arrangement of the reinforcing fibres in a composite part, which determines its directional strength, stiffness and shrinkage.

Fibre volume fraction (Vf)

Fibre volume fraction (Vf) is the part of the volume of a composite occupied by fibres.

Filament winding

Filament winding is a process of laying continuous resin-impregnated fibre onto a rotating mandrel at a programmed angle.

Finite element analysis (FEA)

Finite element analysis (FEA) is a computer simulation of how a part behaves under load.

Forged carbon

Forged carbon is a composite of chopped carbon fibre bundles in resin, hot-moulded under high pressure in a steel mould. It is made by moulding materials such as C-SMC (carbon sheet moulding compound), C-BMC (carbon bulk moulding compound) and prepregs based on chopped carbon fibre.

L

Laminate porosity

Laminate porosity is the volume fraction of voids (air and gas bubbles) in a cured composite.

Light RTM (LRTM)

Light RTM (LRTM – light resin transfer moulding) is a variant of RTM (resin transfer moulding) in which dry fibres are impregnated with resin in a closed composite or aluminium mould: the cavity is evacuated with vacuum and the resin is fed from a pressure pot at positive pressure, usually 1–4 bar.

O

OOA (out-of-autoclave)

OOA (out-of-autoclave) is a group of composite curing methods without an autoclave that give laminate quality close to autoclave quality. It is usually done without additional pressure – using only vacuum and heat, for example in an oven.

P

PCM (prepreg compression moulding)

PCM (prepreg compression moulding) is the pressing of prepreg in a hot, closed mould in a press.

Prepreg

Prepreg is a fibre fabric or tape pre-impregnated with a controlled amount of resin and stored at low temperature.

Pultrusion

Pultrusion is a continuous process for making constant-section composite profiles by pulling fibres through resin and a heated die.

R

RAT – Reverse Autoclave Technology

RAT (Reverse Autoclave Technology), a reverse autoclave, is the curing of composites in an oven whose chamber is under vacuum, with infrared heaters and the laminate pressed by a pressurised bag or bladder.

RTM (resin transfer moulding)

RTM (resin transfer moulding) is a moulding process in which resin is injected into a closed mould containing dry fibres or a preform.

S

SQRTM (same qualified RTM)

SQRTM (same qualified resin transfer moulding) is the curing of prepreg in a closed mould with the injection of a small amount of resin that maintains hydrostatic pressure.

V

Vacuum infusion (VARTM)

Vacuum infusion (VARTM – vacuum assisted resin transfer moulding) is a process in which resin drawn in by vacuum impregnates dry fabrics laid on a single-sided mould under a vacuum bag.

VBO (vacuum bag only)

VBO (vacuum bag only) is the curing of a special prepreg under a vacuum bag only, in an oven, without positive pressure.

W

WCM (wet compression moulding)

WCM (wet compression moulding) is wet pressing: dry fabrics are impregnated with resin just before the mould closes and are then pressed.