Modeling of stable tearing with crack tunneling in specimens of different thickness

Abstract

Stable tearing with crack tunneling in ductile materials has been commonly observed, but a quantitative understanding of the 3D complicated crack tunneling phenomena is very limited. In particular, the correlation between the driving force and fracture toughness during stable tearing with crack tunneling has not been well evaluated. In the current study, modeling efforts have been made to simulate stable tearing events with crack tunneling and slanting under remote tension in A2024-T3 plate specimens of two thickness values (2.286mm and 6.35mm). It is observed that values of CTOD, stress constraint and the Lode stress parameter vary in the specimen thickness direction. For the thinner specimen, a higher stress constraint and a lower CTOD in the midsection of the crack front are found, and the critical CTOD decreases approximately linearly with an increasing constraint and is weakly dependent on the Lode stress parameter. The variations of CTOD, the stress constraint and the Lode parameter in the two plate specimens in the mickness direction are very similar, but the magnitudes of these parameters near the midsection of the crack front increase significantly in the thicker specimen. The approximate linear correlations in the two specimens between constraint and CTOD are not identical, probably due to the coupled effects of constraint and the Lode stress parameter in this midsection region of the crack front.