Analysis of ductile tearing of pipeline-steel in single edge notch tension specimens

The purpose of this work was to develop a three-dimensional finite element model to simulate ductile tearing in pipeline-steels. Two series of experiments and corresponding numerical predictions were conducted on single edge notch tension (SENT) specimens made of pipeline-steel plates, to represent the geometry and loading in a pipeline. In the numerical model, progressive damage was restricted to a predetermined ductile tearing zone. The material damage behavior in this tearing zone was described in terms of a Gurson-Tvergaard (G-T) isotropic constitutive model, which accounts for microvoid nucleation and growth. The criterion for the onset of void coalescence was determined via the Thomason criterion. As a result, the initial void volume-fraction parameter in the G-T model could be identified from experimental results in one SENT specimen. The proposed model was applied to predict the mechanical behavior of SENT experimental results with different plate width, thickness and crack size. The measured load-displacement histories for all SENT specimens were accurately reproduced by the proposed model. The numerical predictions were in good agreement with experimental test data in terms of both the maximum load and the corresponding displacement at maximum load. The proposed model also provides a detailed description of fracture initiation and propagation in ductile SENT specimens.