PSI - Issue 33

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V.P. Matveenko et al. / Procedia Structural Integrity 33 (2021) 925–932 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 8. Strain distributions obtained using DFOS and numerical simulation for different defect size.

The obtained results showed comparable level of average strain in the region of the defect between numerical calculations and experiment. However, it was not possible to measure the profile of the strain gradient obtained by numerical calculation in the defect zone with the help of distributed FOS.

4. Conclusions The study demonstrates one of the possibilities of using distributed FOS for monitoring the mechanical state of engineering structures. Distributed FOS were embedded in the cement sample at the manufacturing stage without any additional protective coating, except for the standard acrylate coating. Despite certain difficulties associated with ensuring the integrity of an optical fiber embedded without an additional protective coating, the work shows the operability of a distributed fiber-optic sensor. The main advantage of this embedding method is that it was possible to avoid the recalculation of strains obtained using the FOS due to the good strain transfer. In the study, a three-point bending experiment was presented in order to test the performance of embedded distributed FOS. Good performance of the sensors in both the tension and compression zones has been shown. The presented experimental data were correlated with the data obtained using numerical simulation, as well as with the data obtained using single point fiber Bragg grating sensors in the experiment carried out earlier. A good correlation was demonstrated between all point and distributed fiber-optic sensors and the results of numerical modeling. As part of the study, the sensitivity of the distributed FOS to the defect introduced into the sample was also shown. It has been demonstrated that a distributed FOS embedded in a cement sample are sensitive to the appearance and development of a defect introduced into structure and can be used for damage detection.

Acknowledgements The research was supported by Russian Science Foundation (project No. 19-77-30008). References

Bao, X. and Chen, L. (2012) ‘Recent Progress in Distributed Fiber Optic Sensors’, Sensors , 12(7), pp. 8601–8639. doi: 10.3390/s120708601. Barrias, A., Casas, J. R. and Villalba, S. (2017) ‘Application study of embedded Rayleigh based Distributed Optical Fiber Sensors in concrete