Cyclic plastic zone and stress-strain evolution in low C-Mn steel ahead of crack under fatigue loading.

Damage assessment due to fatigue crack growth is an important element for assuring structural safety and fitness for service of mechanical components. Under cyclic loading due to the opening and closing of crack, material damage ahead of the crack tip depends on the crack tip blunting, its re-sharpening and the size of cyclic plastic zone. In present parametric study, size of the cyclic plastic zone is evaluated for CT specimen using finite element analysis. Chaboche non-linear kinematic hardening model is used to model elastic-plastic material constitutive behavior. It is observed that cyclic plastic zone size depends on load ratio, load range, load maxima and crack size. The size of monotonic and cyclic plastic zone is compared and found that monotonic plastic zone is approximately three to four times larger than the cyclic plastic zone due to crack closure effect. It is observed that material within the cyclic plastic zone undergo ratchetting. [ABSTRACT FROM AUTHOR]