Long used in the telecommunications industry, fiber optics are now being used as sensors in infrastructure. By using the fiber as a sensor, engineers can continuously monitor the entire length of the fiber, minimizing costs and providing valuable data. When used in structural health monitoring applications the sensors can measure distributed strain, temperature, pressure, and more. But there has been limited research describing the behavior of optical fibers in direct tension. Most have focused on the strain transfer from the host material to the sensing core.
Researchers Maurizio Morgese, Chengwei Wang, Yu Ying, Todd Taylor, and Farhad Ansari wanted to test the behavior of optical fibers in direct tension to determine their mechanical characteristics and develop a theoretical model that predicts the complete stress – strain response. They used two types of optical fiber: ribbon fiber, which is extensively used in structures; and standard single mode fiber (SMF-28) used as the control. Sensors with 4, 8, and 12 optical fiber ribbons were tested, and their mechanical characteristics and stress-strain responses were recorded. The authors were then able to evaluate the correlation between experimental results and the theoretical stress–strain responses obtained using the Ramberg-Osgood law. Their paper “Stress–Strain Response of Optical Fibers in Direct Tension” in the Journal of Engineering Mechanics provides data for the elastic properties of the optical fibers. Learn how you can employ these results to calibrate embedded fiber optic sensors in structural materials, such as concrete, at https://doi.org/10.1061/JENMDT.EMENG-6990. The abstract is below.
Abstract
Stress-strain response of optical fibers in direct tension is introduced in this article. The research involved direct tension tests of optical fibers and development of theoretical relationships describing the tensile behavior of the fibers. Two types of optical fibers, namely ribbon and standard single mode fiber (SMF-28) were included in the experimental and theoretical investigations. The impetus for the study was the need for the elastic properties of the optical fibers, such as the modulus of elasticity and the elastic limit for accurate interpretation of strains measured by optical fiber sensors. Ribbon fibers have proven to be robust for sensing applications in civil structures which prompted the research described herein. By employing the experimental data and by using the generalized Ramberg-Osgood law, it was possible to establish the theoretical stress – strain responses of the optical fibers. The experimental program allowed for distributed measurement of optical fiber strain by a Brillouin Optical Time Domain Analysis system (BOTDA). These results were compared with the direct measurement of the applied displacements at the fiber ends.
Get the details in the ASCE Library: https://doi.org/10.1061/JENMDT.EMENG-6990.
