Numerical and experimental analysis of permeation and cracking behavior of fiber reinforced plastic composites with thermoplastic matrix system

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Achieving greenhouse gas neutrality is essential to limit human-caused climate change. In Germany, this goal is to be achieved by 2045. In the upcoming technological change, hydrogen plays a key role in almost all scenarios as a versatile and - if produced with renewable energies - environmentally friendly energy carrier to ensure the long-term success of the energy transition and climate protection.Among the available storage systems for hydrogen, pressurized storage systems made of fiber-reinforced plastic composites (FRP) represent a promising technology for mobile applications due to their comparatively high storage density and low mass. In particular, scientists and engineers are focusing on so-called multi-cell storage systems, which provide a circuit of cylindrical tank cells and can thus make efficient and flexible use of the available installation space. A disadvantage, however, is the diminished sheath surface -to-storage volume ratio, which means that higher liner wall thicknesses are required to meet permeation and leakage requirements. One solution to this problem is linerless designs (Type-V pressure tanks), in which the FRP simultaneously functions as a support structure and permeation barrier. However, the implementation of the Type-V design requires an in-depth understanding of the permeation behavior of FRP. Due to the highly loaded pressure tank walls, the influence of damage on permeation must be investigated to be able to overcome the challenges through adapted materials as well as structural designs.With this background, the primary objective of the project is the qualitative and quantitative analysis as well as the model-based description of the permeation behavior of continuous reinforced textile composites with thermoplastic matrix (PA 6). For this purpose, experimental methods in the field of CT imaging analysis as well as numerical crack modeling by means of the phase field method will be advanced and used for the analysis of crack patterns. AI-based models for crack prediction, quantification and classification are developed, validated and contribute for future permeation assessment of textile architectures. Furthermore, the influence of crack opening is investigated in in-situ permeation tests and a numerical permeation model is derived. A profound understanding of the correlation between crack and permeation phenomena for composites with textile reinforcement architectures will be provided in order to establish the basis for a successful design and layout of linerless construction-efficient pressure tanks and pipelines.