Evaluation of the equivalent material concept in mixed mode I/III fracture estimation of V-notched Al7075-T6 plates

Abstract

For the first time, performance of the Equivalent Material Concept (EMC) in investigating fracture of V-notched ductile members subjected to mixed tension/out-of-plane shear loading, so-called mixed mode I/III loading, is examined. On the basis of EMC, a ductile material can be equated with a virtual brittle material in order to avoid conducting elastic–plastic analyses. In the present research, a new set of fracture experiments are carried out under several mixed mode I/III loading cases on the V-notched test samples fabricated from Al7075-T6 aluminum alloy and having various notch opening angles and notch tip radii. Combination of EMC with the two stress-based brittle fracture criteria of the point stress (PS) and mean stress (MS) is employed to estimate the load-carrying capacity (LCC) of all the samples tested. Comparing the theoretical predictions with experimental results approves that both EMC-PS and EMC-MS models are accurate in assessing mixed mode I/III fracture of V-notched Al7075-T6 specimens, and both criteria have almost the same efficiency. Additionally, it is revealed that irrespective of the magnitude of the notch opening angle, the predictions of both models about fracture toughness of the V-notched specimens are more accurate for V-notches with smaller notch tip radius.