The role of the fibre in a composite is to provide strength and stiffness
There are four fibres pertinent to Orthotics and Prosthetics
This is a well-known fibre. The material consists of extremely thin fibres that are made up mostly from carbon atoms. The fibres are very long and strong. They align themselves in a length ways orientation. This makes Carbon fibre an incredibly strong material in tension. If compared in weight, carbon fibre is approximately five times stronger than steel. Although strong in tension carbon fibre does not tolerate shock or compression forces very well.
Aramid is often referred to as Kevlar and is a very high strength fibre with great abrasion resistance.
Aramid is strong in tensile strength however its real difference compared with carbon fibre is the durability of its fibres when tensioned over sharp or geometric shapes. Unlike carbon fibre, Aramid can be repeatedly flexed, twisted and pulled without the individual fibres being compromised. Aramid composites are not as brittle and tend not to shatter or splinter.
Aramid is often combined with carbon fibre to prevent catastrophic failure.