Optical fiber fatigue behavior over very extended periods at low stress levels in the field and in laboratory tests

摘要

Abstract: The reliability of optical fiber exposed to relatively high static strains ($GRT 2%) has been extensively modelled and investigated by experiment. Fatigue `knees' have been demonstrated predicting the premature fracture of fiber particularly where elevated temperatures and relatively large volumes of water have been used to soak the samples. The cause has been attributed to simultaneous stress- assisted and stress-free corrosion of the fiber surface. In this paper we show that, a t more moderate strains (1 to 2%) and using a limited volume of water, there is evidence of a strength recovery caused either by a healing process or the observance of some form of lower strain threshold. The expected strength reduction of the fiber, from contemporary models is contrasted to that observed. The unusually high strength retention shown by the test fiber in water is shown to have important implications for optical cable design and for the bending of fiber within joint housings.!10