2D crack growth simulation with an energetic approach

It is well known that the tearing resistance curve J-Deltaa is not a material property. A recent approach, based on an energetic critical parameter to model ductile tearing propagation, is used to model 3D effects. The approach considered in this work aims to estimate the dissipated energy in the fracture process during ductile tearing represented by an intrinsic parameter G(fr). A fracture criterion, which accounts for the crack extension length, is defined and lies on a critical energy release rate, noted G(c), which is compared to G(fr). Previously, this parameter was obtained from a numerical local energy release rate, which handicaps the application field of the approach: a fine mesh for the whole propagation area was needed and the criterion allowed only to model ID propagation. A new manner to estimate G(e) is then proposed in this article, based on the J plastic part variation, which allows to model 2D propagation by defining a local criterion. This new calculation method is validated on a CT specimen made in Tu52b ferritic steel, by comparing the results obtained from the two methods of G(c) calculation. Then, the 2D crack growth case is studied, by modelling the propagation in a ring, loaded in compression. It is shown that a 3D effect, such as tunnel effect, could be successfully represented with this approach. (C) 2002 Elsevier Science B.V. All rights reserved.