For notches, unprotected corners, and holes, JIc is equal to the self-relaxation of the toughness of a material with an equivalent J-integral of zero. The self-relaxation is usually defined as the percentage of material yielding following a single crack. Values of JIc for several engineering materials can be found in Table 1. Illustration of the SIF concept can be seen in Fig. 11, where the greater the JIc, the higher the SIF. Fig. 12 illustrates the stress distribution around a semi-circular corner notch for cast iron. Analysis of these figures suggests that a small change in the SIF magnitude will result in a relatively significant change in the stress field and the current level of cracking occurs at relatively low stress levels compared with the peak stresses. Additionally, the J-integral value provides a quantitative measure of the relative crack-tip plastic deformation to the overall polymer chain and it's analogous efficacy to fracture toughness in a brittle material, independent of the mode of failure. The extension of SIF into complex fracture mechanics is expected to be useful in analyzing structural failure probabilities for higher order modes associated with complex materials such as composites, biomaterials, gels, and foams that experience complex failure modes.
By arranging the controversial ideas of Irwin and Rice‚Äôs paper, it is possible to explore the scope of CLR assumptions and the curvature dependent effects on the SIFs. It is found that SIF values for both a notched and straight cylindrical loading for a plate consisting of an annealed heat-treated rectangular cross-section are identical. This implies that the theory is valid for material of any shape and geometry as long as it does not significantly distort the stress distribution at the end of the crack.
SIFs analysis for a material loaded with a notch, a hole, corner, between holes, and a solid edge enables us to examine the cracks propagation at high strains and stresses. Several authors observe several fundamental aspects based on the SIF study. Using a review of results of SIF analysis on structural materials, Hausner et al. d2c66b5586