Hydrogen is being investigated as aviation fuel, with the objective to achieve an energy transition for the aviation sector. Effective storage solutions are crucial to mitigate the aerodynamic penalty caused by its low volumetric energy density. The focus of this study is the integration of a cryo-compressed vacuum-insulated storage vessel into the primary structure of aircraft, aiming to enhance structural efficiency. This is achieved by implementing analytical methods to analyse the thermo-mechanical loading of the inner and outer walls of the fuel tank. It is envisioned that the inner wall rather than the outer wall is more suitable to sustain additional loads. However, it is unclear how the cryogenic environment affects the stress state of the composite material.

To improve the crashworthiness design of composite aircraft structures, analytical models are useful to enable engineers to have a fundamental understanding of the influence of the design variables. As such, during the preliminary design, this knowledge can be exploited, rather than needing to alter an already mature design in a later phase. Accordingly, an analytical model is derived which allows the determination of the mean crushing load and the energy absorption of composite absorbers. The analytical model allows one to accurately predict the mean crushing load of square tube absorbers while altering their side length and thickness. Moreover, the different terms in the analytical model show that the out-of-plane shearing of the material is the major energy dissipating phenomenon. The composite absorbers are then incorporated into a finite element model of the keel section of the thermoplastic composite subfloor of a fuselage demonstrator developed by the Clean Sky 2 STUNNING project. The analytical model facilitates the estimation of the energy absorption and crash load of the fuselage section augmented with the energy absorbers. In this way, during the preliminary design, the absorbers of the fuselage can be designed concurrently for the static loads and for the crash loading, leading to a more efficient design.