Sensors 2011, 11(7), 6926-6941; doi:10.3390/s110706926

Effect of Coating on the Strain Transfer of Optical Fiber Sensors

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Received: 17 May 2011; in revised form: 27 June 2011 / Accepted: 27 June 2011 / Published: 1 July 2011
(This article belongs to the Special Issue Optical Fiber Sensors)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Optical fiber strain sensors with light weight, small dimensions and immunity to electromagnetic interference are widely used in structural health monitoring devices. As a sensor, it is expected that the strains between the optical fiber and host structure are the same. However, due to the shear deformation of the protective coating, the optical fiber strain is different from that of host structure. To improve the measurement accuracy, the strain measured by the optical fiber needs to be modified to reflect the influence of the coating. In this investigation, a theoretical model of the strain transferred from the host material to the optical fiber is developed to evaluate the interaction between the host material and coating. The theoretical predictions are validated with a numerical analysis using the finite element method. Experimental tests are performed to reveal the differential strains between the optical fiber strain sensor and test specimen. The Mach-Zehnder interferometric type fiber-optic sensor is adopted to measure the strain. Experimental results show that the strain measured at the optical fiber is lower than the true strain in the test specimen. The percentage of strain in the test specimen actually transferred to the optical fiber is dependent on the bonded length of the optical fiber and the protective coating. The general trend of the strain transformation obtained from both experimental tests and theoretical predictions shows that the longer the bonded length and the stiffer the coating the more strain is transferred to the optical fiber.
Keywords: optical fiber strain sensor; Mach-Zehnder interferometer; strain transfer; bonded length
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MDPI and ACS Style

Her, S.-C.; Huang, C.-Y. Effect of Coating on the Strain Transfer of Optical Fiber Sensors. Sensors 2011, 11, 6926-6941.

AMA Style

Her S-C, Huang C-Y. Effect of Coating on the Strain Transfer of Optical Fiber Sensors. Sensors. 2011; 11(7):6926-6941.

Chicago/Turabian Style

Her, Shiuh-Chuan; Huang, Chih-Ying. 2011. "Effect of Coating on the Strain Transfer of Optical Fiber Sensors." Sensors 11, no. 7: 6926-6941.

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