Carbon Fibre Composite (CFRP)
The stiffness laminate. For parts that must not bend — spars, drive shafts, strengthening plates bonded to concrete — where cost is secondary. Stiffer than steel at a fifth of the density, in one direction only.
Properties
- Family
- Composites
- Category
- composite
- Density
- 1.6 g/cm³ · 1600 kg/m³
Densityhow carbon fibre composite (cfrp) compares
Laminate propertiesHigh-strength carbon in epoxy · 65% fibre by volume
- Fibre / matrix
- High-strength carbon · Epoxy
- Fibre volume fraction
- 65%
- Tensile strength, along the fibres
- 2,860 MPa
- Tensile strength, across the fibres
- 49 MPa · 58× lower than along them
- Modulus, along the fibres
- 177 GPa · 10.8 GPa across
- Compressive strength, along the fibres
- 1,875 MPa · Poisson’s ratio 0.27
Values are for a unidirectional laminate of High-strength carbon in epoxy at 65% fibre volume fraction, from fib Bulletin 40 (FRP reinforcement), unidirectional laminate values. Longitudinal means load along the fibres, transverse means load across them; change the fibre fraction or the layup and every figure here changes with it.
Applicationswhere carbon fibre composite (cfrp) is normally specified
Working & joiningtrade experience, not measured values
- Machining
- Machines cleanly but makes conductive dust that must not reach electronics or a live circuit. Cut wet or extract at the tool.
- Joining
- Never bring it into direct contact with a metal fastener in a wet or salty environment: carbon is cathodic to steel and aluminium, so the metal is the part that corrodes. Isolate with glass laminate, a coated washer or a sealant.
- Durability
- Excellent in fatigue and in most chemicals, but brittle in impact and poor through the thickness — a delamination from a hidden impact can leave no visible mark.
As with the wood and metal pages, these lines are not measurements. The longitudinal figures above assume the load arrives along the fibres; a bolted joint is usually the place where it does not, which is why the joining note is the one to read first.
Practical notes
- Conductive: unlike glass laminate, it needs isolating from metal fixings
- Strongly anisotropic — transverse strength is a fraction of the longitudinal figure
- Brittle in impact compared with aramid or glass; it does not yield before it breaks