Fatigue crack-growth from a circular notch under high-levels of biaxial stress

<span style="font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif; line-height: 18px">A series of experiments have been conducted on cruciform specimens to investigate fatigue crack growth from circular notches under high levels of biaxial stress. Two stress levels (Δσ</span><sub style="margin: 0px; padding: 0px; border: 0px; outline: 0px; font-size: 0.8em; white-space: nowrap; line-height: 0.7em; font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif">1</sub><span style="font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif; line-height: 18px">= 380 and 560 MPa) and five stress biaxialities (λ=+1.0, +0.5, 0, −0.5 and −1.0; where λ=σ</span><sub style="margin: 0px; padding: 0px; border: 0px; outline: 0px; font-size: 0.8em; white-space: nowrap; line-height: 0.7em; font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif">2</sub><span style="font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif; line-height: 18px">/σ</span><sub style="margin: 0px; padding: 0px; border: 0px; outline: 0px; font-size: 0.8em; white-space: nowrap; line-height: 0.7em; font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif">1</sub><span style="font-family: Arial, 'Lucida Grande', Geneva, Verdana, Helvetica, 'Lucida Sans Unicode', sans-serif; line-height: 18px"> were adopted in the fatigue tests in type 316 stainless steel having a monotonic yield strength of 243 MPa. The results reveal that fatigue crack growth rates are markedly influenced by both the stress amplitude and the stress biaxiality. A modified model has been developed to describe fatigue crack growth under high levels of biaxial stress.</span>