Abstract
This paper is concerned with mixed mode (combined mode I and mode II) fracture criterion in the case where stable crack growth occurs before unstable fracture. Finite element analyses and tensile tests were carried out on thin sheet specimens of 2024-T3 aluminum alloy having a center crack inclined to the tensile loading axis. The specimen width and the angle between the center crack and the tensile loading axis were changed over a wide range. It was found that stable crack initiation follows approximately the criterion of JI + αJII = JIC, where α is a constant. The direction of stable crack initiation was perpendicular to the tensile loading axis. The net stress at the maximum load was found to be nearly equal to the yield stress of the material tested.
