Influence of fiber cutting at the composite grid intersection on the compressive performance of laminate

Abstract For thick composite grid structure, automated fiber placement (AFP) must be adopted to alternating cut fiber at the composite grid intersection to avoid out-of-plane fiber bending. In the present work, an experimental and numerical study has been carried out to understand and predict the influence of different cutting methods at the composite grid intersection on the compressive failure performance of laminate. Five kinds of test specimens with different cutting ratios were firstly manufactured and tested. A maximum of 67% drop in the compressive strength was recorded for the most severe cutting ratio. A High-speed camera was used to clarify the compressive failure progress of cut specimens. The dominant failure mechanism was classified into fiber fracture failure and inter-ply delamination. Further, numerical simulations were carried out to inform the deformation and failure mechanism of cut specimens. The FEM results correlated well with experiments in terms of location of dominant failure mode and strength knockdown for five different cutting configurations. These findings offered certain practical reference for the design and manufacture of thick AFP composite grid structures.