= Long-fibre composite
A <long-fibre composite> contains reinforcing fibres whose lengths are large enough that end regions do not dominate their load-carrying response. In a well-bonded continuous aligned specimen pulled along the fibres, the fibres and <composite matrix> undergo approximately the same axial <strain>. Their different <Young's moduli> then produce different axial <stresses>, and adding their <forces> gives the <longitudinal rule of mixtures>.
Load enters a fibre through <shear stress> at its interface with the <composite matrix>. Near a free fibre end the axial <stress> must rise from zero, so a short fibre can spend much of its length below its useful load. The <critical fibre length> expresses the associated scale in a simple strength-transfer model. Whether a fibre is mechanically long therefore depends on its diameter, the interface and the required <stress>, rather than on an absolute length in millimetres. Changing fibre direction still changes the response: long reinforcement does not remove <anisotropy>.
Back to article page
