Strength evaluation of continuous curvilinear variable stiffness panels with circular cutouts under biaxial normal loading and off-design conditions

Continuous curvilinear variable stiffness (CCVS) design is explored to improve strength of panels with cutouts compared to straight-fiber laminates. All possible biaxial loading combinations and several force ratios are investigated. A total of 40 optimization problems (40 loading conditions) are solved using a surrogate-based genetic algorithm. CCVS designs provide at least 50% improvement in failure load for all loading conditions over a quasi-isotropic laminate, the baseline. Under off-design conditions, some CCVS designs outperform the baseline for all loading conditions by an average of 52% and 44%, respectively, for a plate with a small and a large hole.