Irwin crack model plastic zone

In the model derived by McClintock and Irwin the shape and size of the plastic zone were calculated by a combination of the stress field at the crack tip (e.g. Eq. (2)) with a yield criterion (e.g. von Mises, Tresca). This leads to the well known dog-bone type of plastic zone showing the influence of stress state. Its form is often approximated to by a circle of radius Tp, where... 

Figure 3.464. Model of plastic zone (Irwin and Dugdale) from crack region [1295].

Figure 7.5 Irwin model of the plastic zone at a crack tip.

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