Assessment of ductile tearing in the analysis of cracked components

New developments performed in the framework of a thesis made by S. Marie have demonstrated that a new criterion, labelled GFR, that measures the energy release rate at the crack tip, can be used to model large ductile tearing for a lot of structural geometries (CT, tube) and materials (ferritic, austenitic, duplex). This energy criterion is therefore a practical alternative to J criterion that is limited to small crack propagations. This new criterion requires only limited developments by comparison to what is available for the application of methods using J: material characteristics, calculation of structural parameters. The GFR value is constant during ductile tearing and can be obtained with a conventional experiment aiming at defining the JR/Δa resistance curve but with a more refined interpretation of this test. First, this new criterion is presented together with the numerical algorithm allowing to calculate it. Its present domain of validation is briefly indicated. The conditions of application of GFR are detailed in order to evaluate the conditions of initiation and ductile tearing in an experiment performed on a cracked tube in the framework of an international program. These applications show that the GFR criterion is operative. It gives satisfactory assessments of large ductile tearing that are not possible with J criterion. As large ductile tearing as 80 mm are taken into account. (authors)