Liquid hydrogen (LH₂) is a promising alternative to reduce carbon dioxide (CO₂) emissions in the aeronautical industry. However, current tanks do not meet their rigorous design and safety requirements. Carbon Fibre Reinforced Polymers (CFRP) offer advantages over classic metallic materials, such as higher stiffness and toughness at low temperatures, as well as lower density. Nevertheless, matrix cracking in composites can cause leaks through the tank walls, compromising their tightness, even with a low crack density. Therefore, a deeper understanding of this phenomenon could prevent permeability loss and ensure the operational safety of the tank. Currently, thermoplastic composites are gaining distinction over thermosets in the aeronautical industry due to their better range of properties and the possibility of out-of-autoclave manufacturing. In this context, CF/PEEK composite has shown greater resistance to damage propagation compared to epoxy-based materials, positioning it as a promising candidate for LH₂ storage tanks. This research evaluates the initiation and propagation of transverse cracks in the matrix in specimens with 0º and 90º layer orientations of thermoplastic (CF/PEEK) and thermoset (M21E/IMA-12K) matrices under static loads and at room temperature. Two different stacking sequences, [0/90/0₂/90₂]s and [90/0/90₂/0₂]s, have been analysed. X-ray tomography images were captured at different deformation states. From these images, crack density was calculated using a digital processing method developed by the authors, which quantifies the number of cracks in each layer across the entire width of the specimen. This method allows for a three-dimensional (3D) visualization of the inspected area, facilitating the tracking of possible paths that could compromise the tightness of the tanks. These results contribute to the design of safer and more efficient tanks for liquid hydrogen storage in aeronautical applications.
Abstract Liquid hydrogen (LH₂) is a promising alternative to reduce carbon dioxide (CO₂) emissions in the aeronautical industry. However, current tanks do not meet their rigorous [...]