Fracture toughness evaluation using circumferentially-cracked cylindrical bar specimens

The present study evaluates the fracture toughness of a rapidly-solidified Al alloy by means of a non-standard procedure. The cylindrical bar specimen used here is characterized by a circumferential notch which is fatigue-precracked under a rotating-bending load. While the J-R curve testing procedure is accomplished with reference to the corresponding ASTM standards, that for data interpretation and qualification is modified to fit the specific conditions of the specimen geometry and material behavior. The measured values of the critical J-integral (J(ic)) fbr crack initiation and the resistance to stable crack growth can satisfactorily account for the effects of constraint and material state, although further studies should be conducted to quantify the data validation criteria. (C) 1997 Elsevier Science Ltd.