Network of optical fiber sensors and method for monitoring the structural health of a composite cryogenic liquid hydrogen fuel tank

A method for monitoring a structural health of a composite cryogenic liquid hydrogen fuel tank including an inner tank, an outer tank and an intermediate chamber between the inner tank and the outer tank, wherein optical fiber sensors are in the inner tank, the outer tank and in the intermediate chamber, the method comprising:

• determining permeability curves (k=f(t)) for a material configuration of the tank as a function of service conditions of the cryogenic liquid hydrogen tank;
• determining a critical k value for the material configuration;
• conducting in-service tests of the cryogenic liquid hydrogen fuel tank by continuously and simultaneously measuring with the optical fiber sensors values of physical parameters indicative of the cryogenic liquid hydrogen fuel tank, wherein the physical parameters include:
• distribution of temperatures in the inner tank,
• distribution of temperatures in the intermediate chamber,
• distribution of temperatures on the outer tank,
• strains at locations on the inner and/or outer tank, and
• pressure in the inner tank and in the intermediate chamber;
• determine a permeability status (k) for the cryogenic liquid hydrogen fuel tank, by analyzing, using the permeability curves, an evolution of the values of the physical parameters during an in-service period of the cryogenic liquid hydrogen fuel tank;
• determine a threshold level of micro-cracks in the cryogenic liquid hydrogen fuel tank by comparing the permeability status (k) to the critical k value, and
• determining, based on the threshold level of micro-cracks, whether to perform a maintenance action on the cryogenic hydrogen fuel tank or to replace the cryogenic hydrogen fuel tank.