The effect of specimen geometry on plastic zone size:: a study using the J integral

In this investigation the nature of the plastic zone ahead of a crack-tip in centre-cracked tension, double-edge-notched tension, single-edge-notched tension, compact tension, extended compact tension, and single-edge-notched bend specimens have been assessed by elastic-plastic finite element analyses at different applied load levels (J integral). The magnitudes of the plastic zone size (PZS) in the investigated specimens have been compared using a new reference standard J/a sigma(y) where a is crack length and sigma(y) is yield stress of the material. The results demonstrate that the PZS is almost invariant with respect to specimen geometry up to a critical value of J/a sigma(y) at a specific a/W ratio. However, beyond this critical value, the magnitudes of the PZS are found to depend on the specimen geometry, which has been attributed to the varying in-plane constraints at the crack tip in various specimens.