Requalification of type IV composite pressure vessels using acoustic emission testing

The growing demand for Type IV Composite Pressure Vessels (CPVs) for hydrogen storage necessitates reliable methods for their re-qualification after service or impact. This dissertation develops and validates an Acoustic Emission (AE) testing methodology to address this challenge. The research combined advanced material characterization, using laser vibrometry to model wave propagation, with a careful designed experimental campaign on pristine and impacted vessels. A network of AE sensors was used during controlled pressurization, following standardized protocols. Key results demonstrate that AE analysis successfully localizes impact damage and distinguishes damaged from pristine vessels. The Felicity Ratio (FR) emerged as a robust diagnostic parameter, showing a strong linear correlation with residual burst pressure; severely damaged vessels exhibited an FR significantly below 1.0. Furthermore, AE reliably identified the "leak-before-burst" failure mode through characteristic high-amplitude emissions. The study established a burst pressure reduction curve, quantitatively linking impact energy to loss of structural strength. This work conclusively proves that AE testing provides a reliable, quantitative basis for the requalification of Type IV CPVs. The findings offer a critical foundation for developing standardized acceptance criteria, enhancing the safety and operational longevity of composite vessels in the clean energy sector.