Safe storage of hydrogen gas in composite pressure vessels is an essential step in the transition towards a hydrogen economy which is believed to play a significant role in the reduction of greenhouse gas emissions. Considering the required working pressure of about 700 bar for hydrogen gas storage, a solid understanding of the mechanical behaviour of filament wound composite tanks under different load cases is crucial. Hence, an analytical and numerical framework to do predictive simulations will be developed in this PhD proposal as this is not well established yet in the state-of the art and it can also support future optimization. Linear elastic material behaviour forms the starting point but is quickly set to be extended with the addition of damage modelling for both static (burst) and fatigue load cases. Next, the influence of manufacturing defects, such as residual stresses, the effect of voids, and varying fibre volume fraction will be integrated in the developed models. Moreover, new testing methods will be established that can partially replace the full-scale tank testing while still representing the complex stress states present in a real tank. As a last step, the generated models will be calibrated and validated with experimental data.