Design, modeling, optimization, manufacturing and testing of variable-angle filament-wound cylinders

Abstract

This work demonstrates the potential of manufacturing variable-angle composite cylinders via filament winding(FW), called VAFW. The proposed design strategy allows different filament angles along the axial direction bydividing the cylinder into regions of constant angle called frames. Designs using two, four, or eight frames areherein investigated. A genetic algorithm is applied to optimize each design for maximum axial buckling load. Adesign with minimum manufacturable filament angle is included in the study. All structures are manufacturedand tested under axial compression, with displacements and strains measured by digital image correlation(DIC). The thickness and mid-surface imperfections of the different designs are measured through DIC and usedto explain the observed buckling mechanisms. These imperfections are incorporated into a nonlinear numericalmodel along with a progressive damage analysis. Additionally, a scaling factor is applied on the measuredimperfections to enable an imperfection sensitivity study on the proposed designs. The VAFW design showsbuckling strength, stiffness, and absorbed energy substantially higher than the constant-angle configuration,attributed to tailored thickness buildup and optimized tow steered angles at particular regions of the cylinder.The experimental and numerical results indicate that VAFW designs can be tailored to postpone buckling sothat the material strength can be better exploited.