PSI - Issue 18

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Valerii Matveenko et al. / Procedia Structural Integrity 18 (2019) 12–19 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 4. Calculated dependencies of the ratios pq a on the hole diameter d . These results allow to conclude that when a hole appears and its diameter increases, the ratios pq a change. At these case these ratios are: 12 a , 15 a , 23 a , 24 a , 25 a , 26 a , 35 a , 45 a , 56 a . Changes in these ratios indicate the appearance and growth of damage. To indicate the defect location, the ratios, which remained practically unchanged, should be analyzed. In the present problem, these ratios are: 13 a , 14 a , 46 a , 16 a , 34 a , 36 a . These data allow to conclude that in the vicinity of sensors s1, s3, s4, s6 defects did not arise, and the defect occurs in the vicinity of sensors s2 and s5. 4. Conclusions A technique for a numerical estimation of the error in the strain values calculated on the basis of physical quantities recorded by FBG sensors glued to the material surface and based on the assumption of uniaxial stress state in FBG is proposed. Based on the assumption of a uniaxial FBG stress state, experimental estimations of the error in the strain values obtained by mounted to the PCM surface FOSS with different orientations relative to the direction of external loads are given. The concept of a numerical-experimental technique is given, which allows for the given options of external loads to register the appearance and development of defects in stress concentration areas, which are determined as a result of numerical modeling of a stress-strain state. The effectiveness of the technique is illustrated on a rectangular sample of a polymer composite material, in which a defect is simulated by a hole, and the defect development by an increase

in the hole diameter. Acknowledgements This study was supported by Russian Science Foundation (project No.15-19-00243). References

Fan, Yu., Kahrizi, M., 2005. Characterization of a FBG Strain Gage Array Embedded in Composite Structure. Sensors and Actuators, A: Physical 121(2), 297–305. Xin, J., Yuan, S., Chen, J., 2019. On Crack Propagation Monitoring by Using Reflection Spectra of AFBG and UFBG Sensors. Sensors and Actuators A: Physical 285, 491–500. Kersey, A. D., et al., 1997. Fiber Grating Sensors. Journal of Lightwave Technology 15(8), 1442–63.