The Effect of Fiber Shape and Spacing on Stress Distribution in a Composite Monolayer with an Internal Crack

The effect of inter-fiber spacing and shape on stress distribution is studied in a composite monolayer. The lamina is subjected to an internal crack while loaded by a force P along the fibers at infinity. Two models are postulated. In the first, fibers have circular cross section while in the second, a triangular shape is considered. By direct application of modified shear – lag model, the differential equations of equilibrium are derived and solved for displacements and stress fields. The results show that the ordinary shear – lag model can not well predict the stress distribution within the lamina. The modified model shows a noticeable decrease in both types of stresses once fiber spacing and shape are changed. This reduction is more pronounced for triangular fibers where a decrease in causes more reduction in maximum shear stresses and no change in fiber normal stresses. The reduction in peak shear stress appears to be 32 percent for volume fraction of one at q = 30o.