Page 157 - Fiber Fracture
P. 157
142 P.K. Gupta
45
40
35
-
S
.c
0
W
-
3
a 30
> -
lo
5
C
l/T (x103 K-’)
Fig. 4. Variation of the stress corrosion susceptibility, N, with temperature, T, for silica fibers (Hibino et al.,
1984).
do not fully model the real cracks in fibers. It is questionable whether the residual stress
state around indentation and abrasion-induced cracks is the same as in the case of real
cracks in fibers. Similarly, the lack of sharpness of the tip in chemically generated flaws
makes them unsuitable to model real cracks (Choi et al., 1990).
In spite of much work on the fatigue strength of fibers, several issues remain not well
understood: (a) the difference in the fatigue behavior of surface versus bulk flaws; (b)
the difference in the fatigue behaviors of large versus small flaws; (c) the role of residual
stresses in modifying the fatigue behavior of flaws.
