PSI - Issue 17

Grigorii Serovaev et al. / Procedia Structural Integrity 17 (2019) 371–378 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

378

8

4. Conclusions

In the paper, the possibility of providing a uniaxial stress state in the vicinity of FOSS based on the use of a capillary tube in the Bragg grating area, was studied. Numerical analysis of the cavity size between the external coating (capillary coating) and the optical fiber showed that for the case of an isotropic material, in which the fiber is embedded, it is possible to ensure the conditions of a uniaxial stress state, uniformity of longitudinal strains along the Bragg grating length, coincidence of longitudinal strains in the optical fiber and in the controlled material, as well as to exclude the contact of the external coating and the optical fiber under the most unfavourable loading case. Numerical calculations showed a slight effect of the elastic modulus of the capillary coating on the cavity size under the load. However, the presence of a cavity in the capillary leads to an increase in stress concentration, which must be taken into account when designing a capillary tube for a particular application. These results confirm the effectiveness of the structural scheme of the capillary in the area of FOSS when embedding optical fiber into the controlled material.

Acknowledgements

This study was supported by Russian Science Foundation (project No.15-19-00243).

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