Carbon Fibre Composites: Deformation Micromechanics Analysed using Raman Spectroscopy

Abstract

In the quest to understand reinforcement by high performance fibres, such as carbon fibres, the development of the subject of composite micromechanics is traced from its earliest roots. It is shown first how, employing concepts introduced by Kelly, it is possible through the use of shear-lag theory to predict the distribution of stress and strain in a single discontinuous fibre in a low-modulus matrix. For a number of years the shear-lag approach could only be used theoretically as there were no techniques available to monitor the stresses within a fibre in a resin. It is then shown that the advent of Raman spectroscopy and the discovery of stress-induced Raman bands shifts in reinforcing fibres, has enabled us to map out the stresses in individual fibres in a transparent resin matrix, and thereby both test and develop Kelly’s pioneering analytical approach.