Essential work of fracture assessment for thin aluminium strips using finite element analysis

The fracture toughness of a commercial thin aluminium sheet (1.2 mm) is measured by the essential work of fracture (EWF) method using a double-edge notch tension specimen. The EWF method is implemented at room temperature at a deformation speed of 2 mm/min. The basics of the EWF method and its relation with J-integral are described in this paper. Ligament yielding is observed to occur at the peak of the load-displacement curve. Following this, necking and tearing occur in the softening region. The EWF for the thin aluminium sheet is measured as 51.5 kJ/m(2). However, the non-essential work of fracture is dissipated in the tearing process after yielding, causing expansion of the plastic region. In this work, two advanced finite element models, namely, non-linear and linear J-Integral finite element models, are implemented to simulate the essential work of fracture test. The results for the essential and non-essential fracture indicate good agreement with EWF fitting. The linear extended finite element (XFEM) model yields more accurate results than the J-integral method. Crack opening displacement is measured by the EWF method, and is compared with the results of the studied models. (C) 2017 Elsevier Ltd. All rights reserved.