Buckling performance of composite panels with two cutouts using streamline-based fibres and stiffeners

Recent studies have shown that the buckling capacity of composite panels containing a single cutout can be significantly enhanced by aligning fibres and stiffeners along curvilinear trajectories that follow the streamlines of fluid flow around arbitrarily shaped cutouts. This paper extends the streamline-based design methodology to composite panels with two cutouts, thereby addressing more complex structural configurations. In particular, the potential flow around two circular cylinders of equal radius is derived analytically using conformal mapping and complex variable theory. Finite element models are developed to perform buckling analyses of unstiffened, longitudinally stiffened, and grid-stiffened panels. Results are obtained for different cutout sizes, boundary conditions, and loading scenarios. The findings confirm that curvilinear fibre and stiffener layouts based on streamlined trajectories substantially improve buckling performance compared with conventional straight configurations. • Streamlined fibres and stiffeners assess buckling of panels with two cutouts. • Potential flow around two equal circular cutouts is derived analytically. • FE buckling analyses cover unstiffened, longitudinally and grid-stiffened panels. • Streamlined fibre and stiffener layouts improve buckling over straight layouts.