Exploration of processability limitations of fiber placement and thickness stacking optimization of thermoplastic composite hydrogen storage cylinders for hydrogen-powered aircraft

Hydrogen-powered aircraft, as a cutting-edge exploration of clean-energy air transportation, impose more stringent requirements for lightweight hydrogen storage due to the limitations of aircraft weight and volume. Composite hydrogen storage cylinders have become one of the preferred solutions for hydrogen storage systems in hydrogen-powered aircraft due to their light weight and high strength. However, during the automated placement of high-stiffness thermoplastic composites (T700/PEEK), fibers may buckle or break in the head section. As the head radius decreases, the overlap of adjacent tows increases, resulting in an increase in the thickness of the polar pores, which is contrary to the light-weighting requirements. To solve this problem, this paper derives the trajectory algorithm as a manufacturing process limitation when thermoplastic fiber bundles are laid without wrinkles, provides a definition of the overlap rate between adjacent fibers, and the effect of different ellipsoid ratios of head profile changes on the overlap of fiber bundles is investigated. The larger the ellipsoid ratio of the prolate ellipsoid is, the smaller the overlap of gaps generated by neighboring fiber bundles is, and the overlap at the pole holes is also smaller, while the change of the oblate ellipsoid is not significant. The prolate ellipsoid has greater application and research value than the oblate ellipsoid in terms of processability, which is of great research significance for the design and fabrication of thermoplastic composite hydrogen storage cylinders for hydrogen-powered aircraft.