Effective thermal and elastic properties of [+θ/−θ]s laminates

This paper presents a set of explicit analytical formulae, some of which have already appeared in the literature, that enable many of the effective elastic, thermal expansion and thermal conductivity properties for unidirectional composites to be calculated in terms of the fibre and matrix properties, and the fibre volume fraction. These properties are required as input values for another set of explicit analytical formulae that are presented, enabling the estimation of the effective elastic, thermal expansion and thermal conductivity properties of balanced symmetric angle-ply laminates. Effective through-thickness properties are calculated in addition to the in-plane properties so that a set of consistent values can be applied to finite element and boundary element analyses of structural elements involving the use of angle-ply laminates, provided that the ply layers in a structure are replaced by the calculated homogenised properties.Examples are given of the application of the various formulae to the prediction of the effective elastic and thermal properties of both CFRP and GRP angle ply laminates for various ply angles, using prescribed representative values of fibre and matrix properties. Zero-expansion laminates and the properties of [±45]s laminates are considered as special cases of interest.