Mechanical testing of optical fibers in the gigacycle fatigue regime

The active application of composite smart materials, which include, in addition to the main material carrying the strength load, optical fibers with optic sensors for condition monitoring, makes the task of determining the strength of the fiber optic sensors itself urgent. Such a task is especially acute in systems subjected to long-term alternating (fatigue) loading, when irreversible damage begins to accumulate in the material. This paper shows a method for determining the fatigue life of specialized optical fibers with Bragg gratings in the so-called gigacycle fatigue regime, when the material resists cyclic loading for more than 10^9 cycles.