TENSILE STRENGTH CHARACTERISTICS OF " PERFECT " SILICA FIBERS

Interactions at the tip of macroscopic cracks in silica glass as they are influenced by time, temperature, stress and water concentration have been studied for some time. On the other hand, the same interactions when they occur at the "perfect" surface of a virgin silica fiber are almost unstudied. The availability of precision-drawn silica fibers for lightguides has afforded an opportunity for such studies. Recent results have shown that such fibers are in fact flaw-free and that the statistical nature of their apparent strength is due solely to diameter fluctuations. It has been found that there are substantial differences between the mechanical behavior of these "perfect" surfaces and that of normal "flawed" surfaces.