Pressure vessels made entirely from fiber-reinforced polymer can generate substantial cost and performance improvements leading to their greater acceptance as a storage medium for pressurized alternative fuels (e.g. hydrogen). Inherent anisotropy and inhomogeneity of fiberreinforced composites usually induces functional failure (i.e. leakage) that precedes structural failure by bursting. Functional failure is attributed mainly to transverse matrix micro-cracking.