Design and Optimization of a Composite Vessel for Hydrogen Storage Subject to Internal Pressure and In-Flight Loads for UAVs

Research is being carried out with the aim of designinga Very-Long Endurance Solar Powered Autonomous Stratospheric UAV. This UAV could play the role of a pseudo satellite and could offer the advantage of allowing a more detailed land vision due to its relative closeness to land (17-20 km) at a much lower cost than a real satellite. Two different configurationsare under investigation in order to decide on the best solution that will completely satisfy the a priori imposed constraints. In recent years, the aeronautical community has increasingly focused on the design of solar powered platforms and zero emission airplanes; a coupled system (solar array and hydrogen fuel cells) can be used to supply energy throughout the entire day in order to ensure the continuous flight for several months. As known, a fuel cell system requires at least a couple of external tanks for fuel storage. Hydrogen and oxygen are stored using a pressure vessel installed inside the wing. In this way, the stored gases are subjected not only to pressure loads but also to in-flight loads that can abruptly change the optimum layout required to satisfy regulation requirements. A parametric analysis has been performed to define the optimum layout and the number of tanks necessary to supply the required power. In addition a genetic algorithm has been used to optimize the laminate layup in order to reduce the weight of the tank and ensure that it can resist without at failing catastrophically.