Validation of the two-parameter fracture criterion for various crack configurations made of 2014-T6 aluminum alloy using finite-element fracture simulations – Part 2 TL-Orientation

Abstract

In the present paper, the two-parameter-fracture-criterion (TPFC) validity and transferability are analysed using two-dimensional (2D) elastic-plastic finite-element fracture simulations with the critical crack-tip-opening-angle (CTOA) fracture criterion and plane-strain-core concept. Fracture simulations were performed on three crack configurations: (1) middle-crack-tension, M(T), (2) single-edge-crack-tension, SE(T), and (3) single-edge crack-bend, SE(B), specimens to predict failure loads and moments. They were made of 2014-T6 (TL) aluminum alloy. Fracture test data from Orange (NASA) were only available on M(T) specimens (one-half width, w = 38–152 mm), which were all tested at cryogenic (−200 °C) temperature. The critical crack-tip-opening-angle (CTOA) and a plane-strain-core height, hc, were selected to match the failure loads on the M(T) specimens. Fracture test data on the M(T) specimens were also used to determine the two fracture parameters (KF and m). All crack configurations were analysed over a very wide range of widths (w = 19–610 mm) and initial crack-length-to-width (ci/w) ratios ranged from 0.05–0.95. The TPFC was shown to fit the M(T) test data (±5%) and the simulated fracture data fairly well (within 6.5%) for all crack configurations for net-section stresses (Sn) less than the material proportional limit (σplσ). For M(T) specimens, a simple approximation was shown to work well for Sn > σpl. Further study is needed for Sn > σpl, for the SE(T) and SE(B) specimens.