Page 159 - Engineered Interfaces in Fiber Reinforced Composites

141

(4

0.8

0.6 t r /
s
a
0.4

b
0.2

I
n I-. I . I . I . I .

Fig. 4.27. Comparisons between experiments and theory of (a) maximum debond stress, cri, and (b) initial
frictional pull-out stress for steel fiber-epoxy matrix composites: (0) uncoated fibers; (0) release agent
coated fibers. After Kim et al. (1992).

1 1
0 = @z) +,a;,(z) +-<(z) , (4.1 13)
1 vi1 1

(4.114)

where y, = b2/(B2 - b2), and B is the outer radius of the composite medium. The
subscript c refers to the composite medium. In addition to Eq. (4.12) for the
relationship between FAS and IFSS, equilibrium between IFSSs and MAS requires