Hydrogen is a promising candidate for achieving aviation sustainability, but storage aboard aircraft presents significant challenges. All-composite, double-walled, vacuum-insulated cryo-compressed storage vessels offer a potential solution by achieving high volumetric and gravimetric efficiencies. Load transfer connections between the tank's shells and the surrounding structure introduce concentrated loads in the composite shells. This work develops analytical models to characterize the stress state in composite shells under discrete in-plane loading, showing how stress concentrations decay and how laminate selection influences the decay rate. Discrepancies between the analytical and numerical models are noted, with suggestions for improving both. Additionally, the current model’s limitations due to the number of roots obtained from the governing equations are addressed by proposing additional boundary conditions. This research supports the structural and thermal analysis of composite hydrogen storage vessels, aiding the adoption of hydrogen as a sustainable aviation fuel.@en

Vacuum-insulated, all-composite hydrogen storage vessels are promising for achieving viable gravimetric and volumetric efficiencies in aviation applications. However, stress concentrations arise due to the connections between the composite shells and to the surrounding structure. This study develops analytical models which capture the stress state of composite cylinders subjected to pressure loading and discrete in-plane edge loads. The models allow for easy adjustments in tank geometry, lamination, and load introduction parameters, including the number and width of connection points. This aids in the preliminary structural and thermal analysis of composite hydrogen storage vessels, pushing the implementation of hydrogen as a sustainable fuel for aviation. @en

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.

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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.

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