Distributed Strain Sensing from Damaged Composite Materials Based on Shape Variation of the Brillouin Spectrum

Abstract

Among fiber-optic distributed sensors, Brillouin optical time domain reflectometry (BOTDR) can effectively measure overall strain in a structure. However, since the spatial resolution of BOTDR is generally more than 1 m, it is difficult to detect inhomogeneous strain distributed within 1 m along a fiber. In this paper, we propose a new technique to detect strain changing sharply within the length of the spatial resolution. This technique is based on the fact that the profile of the Brillouin spectrum changes depending on strain distributions. We confirmed the dependency of the Brillouin spectrum on strain distributions theoretically and experimentally.

Get full access to this article

View all access options for this article.

References

Brown, A.W.et al. 1999. “Brillouin Scattering Based Distributed Sensors for Structural Applications, ” J. Intel. Mat. Syst. and Structures, 10(4): 340-349 .

Cotter, D. 1983. “Stimulated Brillouin Scattering in Monomode Optical Fiber, ” J. Opt. Commun., 4(1): 10-19 .

Dakin, J. and Culshaw, B. 1997. “Optical Fiber Sensors, ” Vol. 4, Artech House, Inc., Norwood, MA .

Horiguchi, T.et al. 1989. “Tensile Strain Dependence of Brillouin Frequency Shift in Silica Optical Fiber, ” IEEE Photonics Tech. Lett., 1(5): 107-108 .

Horiguchi, T.et al. 1992. “Brillouin Characterization of Fiber Strain in Bent Slot-Type Optical-Fiber Cables, ” J. Lightwave Technol., 10(9): 1196-1201 .

Horiguchi, T.et al. 1995. “Development of a Distributed Sensing Technique Using Brillouin Scattering, ” J. Lightwave Technol., 13(7): 1296-1302 .

Kurashima, T.et al. 1994. “Measurement of Distributed Strain in Frozen Cable and its Potential for use in Predicting Cable Failure, ” International Wire & Cable Symposium Proceedings, 593-600 .

Murayama, H.et al. 2000. “Structural Health Monitoring of IACC Yachts Using Fiber Optic Strain Distributed Sensors: a Technical Challenge for America’s Cup 2000, ” In: Proc. SPIE, 3986: 312-323 .

Nanuse, H. and Tateda, M. 1999. “Trade-Off Between the Spatial and the Frequency Resolutions in Measuring the Power Spectrum of the Brillouin Backscattered Light in an Optical Fiber, ” Appl. Opt., 38(31): 6516-6521 .

10.

Shimizu, K.et al. 1994. “Coherent Self-Heterodyne Brillouin OTDR for Measurement of Brillouin Frequency Shift Distribution in Optical Fibers, ” J. Lightwave Technol., 12(5): 730-736 .

11.

Thevenaz, L.et al. 1999. “Monitoring of Large Structure Using Distributed Brillouin Fibre Sensing, ” Proc. SPIE, 3746: 345-348 .