Fabrication and characterization of a magnetized metal-encapsulated FBG sensor for structural health monitoring

A novel means of metal packaging of a fiber Bragg grating (FBG) sensor using stainless steel and tin, together with high temperature resistant samarium cobalt (SmCo) magnet is proposed in this paper. The inclusion of high temperature-capable SmCo magnets enable the metal packaging of the FBG sensor with magnetic capabilities. This packaged sensor can be placed in direct contact with the substrate structures such as iron pipelines and other ferromagnetic components without any adhesives, making them easily detachable and reusable. This is a significant improvement compared with other commercial fiber optic sensors which are, surface attached using epoxies or welded to the substrate. The design parameters and characteristic properties such as load, temperature, and vibration sensitivity of the magnetic metal-packaged FBG sensor are studied numerically and validated experimentally to demonstrate the feasibility of using the encapsulated reusable FBGs for structural health monitoring of compatible structures.