Abstract
The paper presents application of fracture behaviour characterisation results of a dual-phase sheet steel DP600 to an FEA of its deep-drawing for shear fracture prediction. The characterisation results were obtained with the help of a characterisation method based on a tensile test on a novel butterfly specimen and published previously by the authors. The aim of the present paper is to evaluate that characterisation method on a deep-drawing process. Based on the previous results of the authors, the fracture behaviour is modelled here with the help of the modified Mohr-Coloumb fracture model. The obtained FEA results reveal that shear fracture of the studied material is predicted too early by the used MMC fracture model. A novel adjustment of the model is proposed yielding infinitely high fracture strains at strongly pressure-superimposed stress states. As it is often the case in the state-of-the-art fracture characterisation of high-strenght sheet steels, such stress states were not tested during the previously performed fracture characterisation but occur during the studied deep drawing process. With the help of the adjusted MMC fracture model, it is possible to predict the crack initiation moment very accurately and the crack initiation location sufficiently accurately.
Highlights
To fulfil the legal regulations on carbon dioxide emissions, car manufacturers have been using more light-weight materials
The aim of the present paper is to evaluate the fracture characterisation method based on a tensile test on a novel butterfly specimen, which was proposed by the authors in a previous publication [14], on an FEA of a deep-drawing process of a dual-phase high-strength sheet steel DP600
An evaluation of the fracture characterisation method based on a tensile test on a novel butterfly specimen, which was previously proposed by the authors [14], on an FEA of a deep-drawing process of a dual-phase sheet steel DP600 is presented
Summary
To fulfil the legal regulations on carbon dioxide emissions, car manufacturers have been using more light-weight materials. To slow down the anticipated decrease of steel consumption in the automotive industry, steel manufacturers are forced to work hard on continuous improvement of high-strength sheet steel and on efficient solutions for a better exploitation of their high potential in car weight reduction at acceptable costs. Crack initiation at the transition area between the flange and the skirt of a high-strength steel workpiece in a deep drawing process cannot be predicted with the FLC. This type of failure occurs mainly due to plastic deformation in the flange, which takes place under a shear-dominated stress state. Dual-phase steels are prone to such failure due to their microstructure consisting of two mechanically dissimilar phases [4]
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