Application of complementary optical methods for strain investigation in composite high pressure vessel

The work presents the methodology of displacement and strain measurements (in type IV composite high pressure hydrogen and methane storage vessels in areas of the gaseous fuel cell vehicle. The research was conducted in vessels with so called programmed defects in the form of notches and delamination. The complementary optical methods, namely: optical fibre sensing based on Bragg gratings (FBG) and digital image correlation (DIC) method were used for performing local and full-field displacement/strain measurements respectively. It has been shown that DIC can be successfully applied as the method for defect identification in full field of view and that it can support an optimal localization of FBG sensors and their calibration. As FBG sensors are devoted to be integrated with the vessel structure, the proposed methodology constitutes a solution to the difficult problem of building an efficient Structural Health Monitoring (SHM) system for composite high pressure vessels for gaseous fuels. At the same time the measurement data from both systems supports calibration of numerical models of the vessels.