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

The effect of constraint on ductile fracture initiation from a notch tip un der mode I and mixed mode (involving modes I and II) loading is investigate d. To this end, mixed mode fracture experiments are performed with Compact Tension Shear (or CTS) specimen of a ductile 2014-O aluminium alloy. The co nstraint effects are investigated by considering specimens with two crack l ength to width ratios. The effect of crack tip constraint on the relationsh ip between the critical value of the J-integral at fracture initiation (J(c )) and M-p is examined. Further, the micromechanics of mixed mode ductile f racture initiation is investigated by performing fractographic studies and metallographic examination of the mid-plane region of the specimen near the notch tip. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science L td. All rights reserved.