VISUAL END-OF-LIFE CRITERION FOR COMPOSITE HIGH PRESSURE VESSELS FOR HYDROGEN STORAGE

The storage of hydrogen at pressures clearly presents a challenge to designers of pressure vessels to ensure their utmost reliability. At present there is a paucity of information on the reliability of carbon fibre composite pressure vessels which are intended for use over periods of decades and those testing procedures which are mentioned in standards have been shown to be largely unsuitable as they are based on the failure of metal structures. This study deals with failure and failure prediction in advanced fibre reinforced composite pressure vessels: The aim of this study has been to evaluate the possibility of providing a simple, cost effective and unambiguous visual means of detecting approaching failure at a stage when the pressure vessel can be safely removed from service. It is proposed to benefit from the wide family of carbon fibres which is produced so as to add a layer of carbon fibre composite material, the fibres of which have the same stiffness as the carbon fibres in the bulk of the structure but which possess lower strength. The failure of this layer would provide advanced warning of progressive and unacceptable damage to the pressure vessel and would avoid any ambiguous interpretation.