Fabrication Stresses in Graphite-Resin Composites

Residual thermal stresses are present in cross-plied graphite-epoxy composites due to the anisotropic thermal and mechanical properties of the individual layers. Experimental measurements and analytical calculations of the thermal stress induced in two different cross-plied composites during fabrication are presented and shown to be in good agreement. The occurrence of cracking in certain composites is explained in terms of the transverse tensile strength of the unidirectional composite layers and the stress developed during fabrication. Two approaches are presented to avoid cracking during fabrication.