Strain measurement technique for the cryogenic composite tanks using FBG sensor

Although CFRP composites are widely used in spacecraft structures, there are few technologies to assess the structural integrity during the flight. A health monitoring that diagnoses the structural integrity in real-time is well known as one of the advanced technologies. Fiber optics sensors, especially fiber Bragg grating (FBG) sensors, are candidates for the sensing devices used for the health monitoring technology. FBG sensors have many advantages in comparison with the conventional sensors such as immunity to electromagnetic interference, light weight, small dimensions and so on. In this research, the strain measurement of a composite LH2 tank was attempted using FBG sensors through the cryogenic pressure test, This tank will be mounted on the reusable rocket vehicle test (RVT) operated by the Institute of Space and Astronautical Science (ISAS). The real-time strain measurement in the rocket operation would enhance the reliability of the composite tanks and contribute to the practical use of RVT.