The mechanical reliability of optical fiber is critically important for many engine sensor applications where the fiber is subjected to cyclic loading, high temperature, and oily, acidic environments. We have investigated the effect of buffer coatings on the cyclic fatigue behavior of fused silica fibers. Aluminum, polyimide, uv- curable epoxy acrylate, and Tefzel coated fibers were tested at room temperature and after exposure to heat and oil. Cyclic fatigue was measured using a test fixture that simulates the motion of a piston in an internal combustion engine. The results indicate that the selection of buffer coating is an important consideration in determining mechanical reliability of optical fibers in this application.
Harvey N. Rogers,
"Cyclic fatigue behavior of silica fiber", Proc. SPIE 1366, Fiber Optics Reliability: Benign and Adverse Environments IV, (1 February 1991); doi: 10.1117/12.47685; https://doi.org/10.1117/12.47685