Type of carbon fibre used in F1 car

[akbar21881]

Is there a difference in properties between the woven type of carbon fibre and the unidirectional type of carbon fibre?

For Uni-directional carbon fibre( eg AS4/8552) the longitudinal and lateral properties differ due to difference in the coefficient of thermal expansion and also the poison ratio. This can be easily explained because the fibre is aligned in one particular direction only.

But for woven type, isn’t the property is similar in both longitudinal and lateral direction? If so, does this means that all theories applicable and developed for uni directional types are not applicable to the woven types?

[Guest]

akbar,

Carbon (graphite) fibers are only really capable of carrying loads in tension. You can't push on a string, right?

A composite material, like carbon-reinforced-epoxy, is only as good as the epoxy resin in compression and shear. But as long as the load puts the graphite fibers in tension, which is how you should design a composite part, the mechanical properties for uni-directional graphite fibers should apply.

But per your question, stresses in the longitudinal and lateral directions within a composite structure can vary greatly, depending upon the fiber placement/layup/orientation and the ratio of resin to fiber within the finished product.

As for CTE, I would guess that the composite material would be limited longitudinally by the graphite CTE value and transversely by the resin CTE value.