Plastic zone ahead of Fatigue Crack tip

Monotonic and reversed plastic zone development at tip of advancing fatigue crack

• Hahn et al. measured the reversed plastic zone dimension as

• Paris showed that the size of this smaller plastic zone was

• Plastic zone size is estimated by substituting hk for K and 2σys for σys in normal plastic zone size formula.

Plastic zone size

2

033.0

ys

cy

Kr

2

8

1

ys

ky

hr

Cyclic strain softening

Cyclic strain hardening