Single-valued strength of ‘‘perfect’’ silica fibers

An analysis has been made of the tensile strength statistics of two silica fibers with quite different degrees of diameter uniformity. It has been found that the coefficient of variation in diameter (νd) is equal to that in minimum diameter (νd,min) and that the measured coefficient of variation in breaking load (νL) and breaking stress (calculated assuming constant d) are twice this value. Since νL =νσ =2νd =2νd,min it is clear the apparent variability in strength is the result of the variability in diameter and therefore the real strength is essentially single valued. Because of this lack of statistical variation in breaking strength, it is suggested that these fibers are flaw-free as drawn.