Matrix crack growth

When d is sufficiently small, Eqn. (40a) applies and 3,ip is independent of the stress. Once this occurs,, ip cannot increase and is unable to satisfy again the matrix crack growth criterion (Eqn. (24)). This occurs with spacing, ds, at an associated stress as (Fig. 1.11). This saturation spacing is given by... 

Fig. 1.33 The matrix crack growth mechanisms that operate in 2-D CMCs.

Fig. 6.18 Schematic representation showing how a reduction in the bridging force by interface wear leads to matrix crack growth. The fibers carry the applied load across the matrix cracks, reduing the crack opening displacement and the net stress intensity (Klip) at the tip of matrix cracks. If the interfacial shear stress t decreases during fatigue, then the bridging stress p(x) decreases, leading to a reduction in Kp. This reduction increases Kfy, which can cause the further extension of a matrix crack.

Ceramic-matrix fiber composites, 26 775 Ceramics mechanical properties, 5 613-638 cyclic fatigue, 5 633-634 elastic behavior, 5 613-615 fracture analysis, 5 634-635 fracture toughness, 5 619-623 hardness, 5 626-628 impact and erosion, 5 630 plasticity, 5 623-626 strength, 5 615-619 subcritical crack growth, 5 628—630 thermal stress and thermal shock, 5 632-633... 

It should be noted that a mode 11 crack-resistance R-curve may also be obtained for some fiber-matrix systems (Vu-Khanh, 1987). In conjunction with the mode 1 R-curve the additional information of a mode 11 R-curve will be of great use to the composite design engineers. This is increasingly the view of the ESIS task group on delamination crack growth resistance. 

S. Groh et al Fatigue crack growth from a cracked elastic particle into a ductile matrix. Phil. Mag. 88, 3565-3583 (2008)... 

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