Probabilistic Failure Prediction for Silica Optical Fibers Based on the Exponential Law

Abstract

This study presents a reliable method for allowable stress predictions for silica optical fibers based on a probabilistic failure theory. The key to accurate predictions is the use of a crack growth law in which the crack velocity increases exponentially with the applied stress intensity factor. Such a growth law, i. e., an exponential law, can explain crack growth behavior of silica optical fibers better than the commonly used power law. Using the exponential law, we derive useful equations providing relationships between failure probabilities and allowable stresses for optical fibers in long-term service situations after proof testing. By comparing allowable stresses predicted based on the equations with those predicted using the power law, we also discuss risks of the use of conventional prediction methods based on the power law.