Simple inverse FEM based procedure of flow curve extraction applied to unirradiated and irradiated 73 W weld material

Abstract

The H2020 FRACTESUS project is aimed to validate miniaturized compact tension specimens usage for fracture toughness characterization of irradiated materials. One of the tasks in the project is devoted to the numerical simulations of the 0.16T and 1T-CT specimens and comparison of their stress/strain fields in. For this purpose accurate material flow curves are necessary to derive comparable mechanical response between the numerical models and experiments. This paper presents a simple technique of flow curve extraction from the tensile test using engineering stress–strain data. The proposed method utilizes a coarse meshed Finite Element Model and a manual flow curve data optimization procedure without additional scripting. The robustness of the method was shown on the example of the 73 W weld material in the unirradiated and irradiated states, tested at various temperatures from −100 °C to 125 °C. The obtained numerical flow curves are in a very good agreement with the experimental results. Moreover, the advantages of the proposed method were shown over either the methods based on extrapolation of the predictions of popular models with parameters fitted to prior necking or the method based on fracture diameter measurements. The final validation of the proposed methodology was demonstrated by numerical simulations of fracture toughness tests on precracked Charpy specimens.