The development of robust hydrogen storage systems is vital for the widespread adoption of hydrogen as a clean energy source. At the Department of Polymer Engineering, several ongoing research projects are investigating crack initiation and propagation in fibre-reinforced composite pressure vessels designed for compressed hydrogen (“DigiTain”) and liquid hydrogen storage (“Cryofuselage and “INTAKT”). These projects focus on vessels manufactured using advanced filament winding techniques, which optimize material distribution and enhance mechanical performance. A key area of interest is the fracture mechanics of these composites under the unique stresses posed by hydrogen storage. For compressed hydrogen vessels, working at pressures up to 700 bar, crack initiation and propagation due to cyclic loading and pressure variations are analysed. In liquid hydrogen vessels, the focus shifts to understanding the effects of cryogenic temperatures, where thermal contraction can induce micro-cracking and affect the long-term structural integrity. [1]

Figure 1. Measurement results of crack propagation tests for epoxy resin toughened with different additives aimed for the application in compressed gas pressure vessels (left) and fracture toughness test results for different volume percentages of W36 block-copolymer toughener at varying temperatures (right).

The selection of appropriate epoxy resin systems and their combination with tougheners is a critical factor in material design. Fracture mechanical tests, including fracture toughness evaluations and fatigue crack growth rate measurements, are employed in different works to assess the material behaviour. Additionally, thin-ply filament winding plays a crucial role in enhancing crack resistance by improving load distribution and reducing stress concentrations.[2]

References
[1] F. Hübner et al., Polymer Testing, 2022, 113, 107678.
[2] E. Szpoganicz To be published