Improving the extension–twist coupling performance of practically warpage-free laminates via layup hybridization

Abstract

This article investigates whether the extension–twist and bend–twist coupling performance of practically warpage-free laminates can be improved by layup hybridization (carbon/epoxy–glass/epoxy hybrids) compared to non-hybrid (mono) laminates. We performed numerical layup search by simulating the thermal warpage, and the bend–twist and extension–twist behaviour of 4096 4-ply layup permutations. The upper limit of allowable manufacturing-induced warpage was based on the ISO2768 standard. The optimal hybrid and mono layups were selected to have the most significant coupling performance within the allowable warpage range. A mono layup achieved the maximum bend–twist performance (which does not require layup asymmetry), but layup hybridization increased the extension–twist performance by more than 30% in the practically warpage-free range. The numerical results were validated through 3D scanning and 3D digital image correlation–aided mechanical tests. We concluded that layup hybridization can significantly improve the extension–twist performance of realistically usable composite laminates with negligible thermal warpage.