Validation of the two-parameter fracture criterion for various crack configurations made of 2014-T6 aluminum alloy using finite-element fracture simulations – Part 1 LT-Orientation

Abstract

A two-parameter fracture criterion (TPFC), derived by Newman, related the linear-elastic stress intensity factor, KIe, and net-section stress, Sn, at failure with two material fracture parameters, KF and m. The objective of this work was to validate the TPFC using two-dimensional elastic–plastic finite-element analyses (FEA). The critical crack-tip-opening-angle (CTOA) fracture criterion and a plane-strain core were used to match the failure loads on middle-crack-tension, M(T), specimens made of thin-sheet 2014-T6 (LT) aluminum alloy. The same analyses were then used on other M(T), single-edge-crack-tension, SE(T), and bend, SE(B), specimens to predict failure loads and moments. Test data was not available on SE-type specimens. A wide range in specimen widths (w = 19–610 mm) were considered. The finite-element code, ZIP2D, was used to calculate critical stress-intensity factors at failure corresponding to all crack configurations for crack-length-to-width (ci/w) ratios of 0.05–0.95. The FEA results agreed very well with the TPFC predictions for net-section stresses less than the material proportional limit. Further studies are needed for net-section stresses greater than the proportional limit on both tension and bend specimens.