Investigation of optical fibers as sensors for condition monitoring of composite materials

摘要

In relation to the concept of smart skins and structures two optical bow-tie fibers with different beat length have been investigated as sensors. For the particular fiber type a sensor system has been built up based on measuring the light intensity and calculating the phase difference in the fiber. The system is composed of standard optical components and constitutes the calibration unit for optical sensors. Experimental results using both fibers are presented, where the external actions are strain and temperature. The fibers are exposed to strain and temperature by a spindle device and an electrical furnace, respectively. This procedure is assessed by gluing the fiber onto a cantilever beam and surrounding the fiber by hot water. The experiments show a good linear relation between the optical phase difference in the fibers and the external perturbations, especially for the strain experiments.