Monitoring Microcracking and Leakage of a Hydrogen Tank Using Fiber Optics and the Thermal Expansion

The structural health monitoring (SHM) of microcracking in cryogenic hydrogen storage tanks is a critical aspect for ensuring long-term safety and operational reliability. Early detection of such damage can prevent leaks and structural failure, making the development of sensitive, non-intrusive diagnostic techniques essential. In this study, a series of experimental tests were conducted to evaluate the feasibility of using thermal expansion behavior as a potential SHM indicator. The material under investigation was a carbon–epoxy composite laminate (M21/IMA) with a [0/90]2s layup, representative of those used in cryogenic aerospace applications. Artificial microcracks were introduced at cryogenic temperatures (approximately 20 K), followed by thermal expansion and gas permeability measurements. The objective was to explore the correlation between induced damage and measurable physical changes, with the aim of assessing the viability of this approach for future SHM strategies in liquid hydrogen tank systems.