Hydrogen is a leading candidate for zero-emission propulsion in aviation, particularly when stored and utilised in its liquid form. However, key components such as composite cryogenic pressure vessels remain at low Technology Readiness Levels (TRL), requiring further investigation into their structural performance under realistic operational conditions. The present work aims to provide a validated numerical methodology for simulating the thermomechanical behaviour and the progressive damage evolution of composite cryogenic hydrogen tanks. The finite element framework incorporates ply-level failure criteria and stiffness degradation laws to capture intra-laminar damage mechanisms under combined pressure and temperature loads. The modelling approach is validated against experimental data from coupon-level open-hole tension tests and subcomponent-scale composite pipes burst tests, demonstrating strong correlation in terms of failure onset and progression.

The validated methodology is subsequently applied to a demonstrator, comprising a composite liquid hydrogen tank, subjected to three representative loading scenarios: internal pressure, cryogenic temperature and combined cryogenic-mechanical loading. Results reveal that matrix-dominated damage initiates near the cylinder – dome interfaces of the tank and propagates across the laminate, while fibre failure is not observed in the investigated load cases. This suggests that potential hydrogen leakage is the initial critical failure condition that occurs before any other important structural damage of the tank, highlighting the need for appropriate tank design. The performed study contributes to the understanding of structural integrity of composite cryogenic tanks and offers a computational basis for future design and certification efforts in hydrogen aviation systems.