Composite over-wrapped pressure vessels are the state-of-the-art for hydrogen storage, with Type IV vessels currently using a thermoplastic liner and a thermoset composite. The next innovation, Type V vessels, aims to use a thermoplastic composite over-wrap that acts as both the barrier and container, requiring new materials and manufacturing methods like automated fibre placement.

To accurately characterize the new materials, the effect of their manufacturing process must be captured. While the standard split-disk test exists for wound specimens, it underpredicts their burst strength and fatigue life. Other attempts in literature have improved strength estimations but are not viable in fatigue, thus creating a challenge.

A new test method was developed, which uses a polyurethane ring to apply cyclic internal pressure. It was designed through finite-element analyses, fine-tuned through rigorous tests, and benchmarked against the standard method. It showed improved strain distribution and near-consistent performance in fatigue tests. Hence, it demonstrated potential for more accurate static and fatigue strength characterization of wound composites, with room for improvement through better alignment and even friction.