Fatigue crack growth rate in aluminium alloy including Mixed Mode I and III

The paper contains results of experimental tests on the fatigue crack growth rate of AlCuMg1 aluminium alloy for Mixed Mode I and Mode III in conditions of different stress ratios $ R$. For the tests, plane specimens with an external unilateral sharp notch as the stress concentrator were used. The tests were done for a constant moment amplitude under bending with torsion. The results of experimental tests were described by a nonlinear formula based on the $ {\Delta}J$-integral range. The change of the stress ratio $ R$ from $ -1$ to $ 0$ caused the fatigue crack growth rate. The proposed formula for description of the fatigue crack growth rate, including the $ {\Delta}J$-integral range, satisfactorily described the results obtained experimentally for AlCuMg1 aluminium alloy.