Effect of fibre transverse isotropy on micro-residual stresses in polymeric composites

In this paper, the influence of transversely isotropic behaviour of the fibre on micro-residual stress fields is investigated. For this purpose, the energy method is utilized to predict the micro-structural stresses in polymer matrix composites under uniform thermal loads. The representative volume element (RVE) considered here includes a transversely isotropic fibre embedded in an isotropic polymer matrix. Based on the energy method, a three-dimensional closed-form solution for micro-residual stresses is obtained. The analytical results are evaluated with a finite element solution. The analysis shows that the transversely isotropic behaviour of the fibre greatly increases the fibre and matrix axial residual stresses in comparison with the isotropic fibre assumption. Fibre anisotropy has a significant effect on the interfacial shear stress distribution, in contrast with the interfacial radial stress field. Both the finite element solution and analytical method result in a similar behaviour for micro-residual stresses distribution along the fibre length. However, the finite element method cannot satisfy the stress-free condition for the residual shear stress at the fibre end due to the stress singularity.