Origins, effects, and characterisation of residual strains in composite materials

Properties of all composite materials are influenced by residual strains to a certain extent, which can either be deleterious or beneficial. This paper reviews the characterisation techniques for these ubiquitous strains and discusses their effects on the mechanical and fracture properties. The techniques range from relatively simple mechanical testing through to the more sophisticated diffraction techniques which rely on x-ray or neutron diffraction. Recent research on some ceramic composites are presented to further illustrate the use of these strain characterisation techniques and correlate the strain-fracture property relationships. (authors)