Gas permeability of CFRP cross-ply laminates with thin-ply barrier layers under cryogenic and biaxial loading conditions

Utilization of carbon fiber reinforced plastic (CFRP) composite materials in propellant tanks is expected to drastically reduce the structural weight of space vehicles. However, fuel leakage through the chain of matrix cracks caused by serious thermal residual stress is a considerable problem. To avoid fuel leakage, this study proposes leak barrier layers consisting of thin-ply prepregs. Biaxial tensile tests are performed for specimens with or without thin-ply barrier layers at cryogenic temperature, and the gas leakage properties of damaged CFRP cross-ply laminates are investigated. In addition, the formation of leakage paths at cryogenic temperature is simulated by the finite element method based on the experimental data. Finally, the experimental and numerical results demonstrate that thin-ply barrier layers increase the tolerance against damage and leakage.