Buckling optimization of variable stiffness helicoidal composite laminates based on semi-analytical method

Abstract

Variable stiffness laminates and helicoidal composites have gained significant attention in recent years. This paper introduces a novel structure called variable stiffness helicoidal composite laminates, which combines these two materials. The fibers in each layer are arranged in curved paths, and all the layers are stacked in a helicoidal pattern. To ensure uniform thickness throughout the laminate, an equidistant placement method is proposed for designing the curvilinear fibers. By establishing the energy equation and fitting the displacements with Legendre polynomials, a semi-analytical method is proposed to determine the critical buckling load. An integrated design framework is developed to obtain the optimal design. The optimized models show more than 10% enhancement in the critical buckling load compared to the quasi-isotropic laminate under uniaxial compression and in-plane shear.