An experimental investigation of constraint effects on mixed mode fracture initiation in a ductile aluminium alloy

The effect of constraint on ductile fracture initiation from a notch tip under mode I and mixed mode (involving modes I and II) loading is investigated. To this end, mixed mode fracture experiments are performed with Compact Tension Shear (or CTS) specimen of a ductile 2014-O aluminium alloy. The constraint effects are investigated by considering specimens with two crack length to width ratios. The effect of crack tip constraint on the relationship between the critical value of the J-integral at fracture initiation (Jc) and Mp is examined. Further, the micromechanics of mixed mode ductile fracture initiation is investigated by performing fractographic studies and metallographic examination of the mid-plane region of the specimen near the notch tip