where A, the mirror constant, is a parameter found empirically. It has been
found that for all glasses considered here, the ratio of the mirror radius, r
m
and
the original flaw size, c, is approximately 0.1. From Eq. (24.19), it can be seen
that A has the units of stress intensity and is essentially proportional to K
IC
.
If c r
m
=10, then, K
IC
0:4A.
24.7 PROOF-TESTING AND RELIABILITY
As we have discussed earlier, the majority of the length of fiber has an
extremely high strength, but occasional weak defects are encountered, which
are introduced during manufacturer. These weak defects control the practical
reliability of fiber that is of useful length (i.e., more than a few millimeters).
Review of Eq. (24.9) for the Weibull strength distribution shows ...