Evaluation of gas leakage through composite laminates with multilayer matrix cracks: Cracking angle effects

Gas leakage through a damaged network in composite laminates is experimentally evaluated to assess fuel leakage in relation to the applicability of high-performance composites to cryogenic propellant tanks of space launch vehicles. Using [02/θ2]S (θ = 45, 60, 75 and 90) laminates, matrix cracks in 0° plies are induced by three-point flexural loading and subsequent uniaxial tensile tests of laminates in 0° direction to produce matrix cracks in all constituent plies of the laminates. Helium gas leak rates through the damaged laminates subjected to uniaxial loadings are measured using a helium leak gas detector at room temperature. The effect of intersecting angles of matrix cracks on gas leakage is discussed using the simple leak model based on leak conductance at intersections of matrix cracks.