The main objective of this study is the development of an embedded fiber optic sensor for testing ceramic composites in a very high temperature environment. The sensing element is an optical grade sapphire fiber operating on the principle of spatial modulation in a multimode waveguide. In order to employ this waveguide as a stress sensor, optomechanical testing has been performed to examine the optical response to external stresses. Several tests, including tension, micro-bending, and lateral compression, are in progress. These tests will establish the basis for using embedded optical sensors for characterization of ceramic composites in real environment. The principles of operation and experimental investigations on the microbending tests are presented in this paper. The results show that the developed sensor can be applied for stress monitoring as well as displacement measurements in a very high temperature environment.
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