Investigation Of The Mechanical Behavior Of Low Strength Fibers

Abstract

The mechanical reliability of long lengths of optical fibers is controlled by large flaws that occur so infrequently that they are unlikely to appear in the short lengths of fiber ordinarily tested in the laboratory. Current mechanical reliability predictions are based on data obtained from short lengths of high strength fiber, but there is some concern that these data may not apply to the critical, large flaw sections. We have produced long lengths of low strength fibers with narrow strength distributions by directing a jet of abrasive particles against the fiber surface before coating. Static and dynamic fatigue testing of the low strength fiber showed that the crack growth exponent, n, increased with decreasing strength. Since larger values of n are associated with slower crack growth, the use of smaller n values obtained from high strength fibers results in conservative reliability predictions.