Today, composite pressure vessels for the storage of hydrogen are of special interests. Besides the bearing of the operation pressure, the permeability of the composite, especially after loading, is a main focus of current investigations.
Within this paper an experimental method for the analysis of the gas leakage and permeability properties of damaged and undamaged composites is presented. Therefore, a permeability test rig was developed. For validation the permeability properties of a thermoplastic fiber reinforced composite sample as well as a thermoset sample of tension strut reinforced conformable vessel were investigated. Afterwards, the thermoplastic sample has been impacted and the strut reinforced specimens have been loaded cyclically. The change in leakage properties were investigated and the damage structure analyzed by contrasted computed tomography measurements. While the undamaged composites show sufficient barrier properties and gas transport is mainly driven by diffusion, the composite samples after loading showed an increase of the leakage rate by 2 orders of magnitude and the analysis of the microstructure showed through-the-thickness damages which allowed gas flows.