Crack meeting interface

Figure 16.6. (a) A crack meeiing an interlace between two materials, (b) Experimental arrangcmem for observing a peel crack meeting an interface between two materials. 

The problem of a crack meeting an interface in a composite as shown in Fig. 16.6(a) was posed by Cook and Gordon who wrongly concluded that the strength of the interface was important. Zak and Williams followed by Rice and Sih" also studied this problem using elastic stress analysis, but the problem was complicated mathematically and led to strange oscillating stresses near the crack... 

Figure 16.10. A crack meeting an Interface penetrates and deflects equally when the ratio of cohesive and adhesive energies is a constant.

S. V. Nair and T.-J. Gwo, Role of Interface in Creep Crack Growth of a Fiber Reinforced Composite at Elevated Temperature, Paper presented at the 95th Annual Meeting of the American Ceramic Society, Cincinnati, OH, April, 1993. 

When a lap joint fails completely, the initial crack in the fillet is turned to run along (or close to) the adhesive-adherend interface. It meets a similar crack running in the opposite direction and we have the familiar result shown schematically in Fig. 26. 

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