Manufacture and Buckling Test of a Variable-Stiffness, Variable-Thickness Composite Cylinder Under Axial Compression

Variable-angle tow (VAT) manufacturing methods significantly increase the design space for elastic tailoring of composite structures by smoothly changing fiber angle and ply thickness across a component. Rapid shearing (RTS) is VAT technique that uses in-plane (rather than bending) to steer tows dry or pre-impregnated fibers. RTS offers number benefits over conventional bending-driven steering processes, including tessellation adjacent courses; no overlaps gaps between tows; wrinkling bridging. Further this, an additional variable: orientation coupling due volumetric relation tow’s width. Previous computational work has shown through judicious choice curvilinear trajectories along cylinder’s length its circumference, imperfection sensitivity cylindrical shells under axial compression can be reduced load-carrying capacity increased. The present aims verify these predictions testing two cylinders: cylinder straight-fiber, quasi-isotropic as benchmark. tow-steered process, measurements, instrumentation, buckling tests both cylinders are discussed herein. experimental results compared against high-fidelity geometrically nonlinear finite element models include measured geometric loading imperfections before during tests. Finally, discussion provided on outstanding challenges in designing primary aerostructures.