Effect of Stress Ratio on the Mixed Mode (I/II) Fatigue Crack Growth in Al 7075-T6

The effect of stress ratio on the mixed mode (I/II) fatigue crack growth (FCG) rate has been studied. Fatigue experiments are performed under three different stress ratios using compact tension shear (CTS) and compact tension (CT) specimens fabricated from Al 7075-T6. The modified Paris law and the Walker equation are used for modeling the stress ratio effect. The finite element simulations of the FCG are performed in ANSYS® APDL, and the variation of stress intensity factors with the crack growth is calculated. The results show that the Walker equation accurately predicts the stress ratio effect on the FCG rate.