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

• Published in: Engineering fracture mechanics Vol. 206; pp. 201 - 217
• Main Authors: Malki, Mounia, Himmiche, S., Newman, J.C.
• Format: Journal Article
• Language: English
• Published: New York Elsevier Ltd 01.02.2019; Elsevier BV
• Subjects: Alloying elements; Aluminum alloys; Aluminum base alloys; Configurations; Crack tips; Crack-tip-opening angle; Cracks; Criteria; Cryogenic temperature; Edge cracks; Finite element; Fracture; Fracture testing; Parameters; Plane strain; Plane-strain core; Proportional limit; Simulation; Stress-intensity factor; Two dimensional analysis; Cracks; Fracture; Stress-intensity factor; Crack-tip-opening angle; Plane-strain core; Finite element
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2018.11.004

•Fracture data on 2014-T6 (TL) aluminum alloy M(T) specimens were analyzed.•Fracture data showed linear relation between stress-intensity factor and net-section stress at failure.•Finite-element method used to conduct fracture simulations using critical crack-tip-opening angle fracture criterion.•Three crack configurations, M(T), SE(T) and SE(B), were analyzed.•Two-parameter fracture criterion correlated simulated fracture data on three crack configurations reasonable well. 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.