Investigation of the formability of ductile sheet materials under non-proportional loading with consideration of the anisotropic damage behaviour

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The determination of the formability of sheet materials is an important step in the design of sheet metal components. Since complex components have a non-linear deformation history, a description by means of a linear limit shape change curve is not sufficient because the remaining formability as well as the failure mode significantly depend on the deformation history. Within the framework of this research project, it should be possible to predict the deformability after non-proportional loading paths with a change in the loading direction. For this purpose, two materials, AA6xxx and DP600, are systematically investigated in order to obtain their forming capability and the failure mode after a complex deformation history. With the help of numerical simulations, a damage model is created, which isintended to map the deformation and failure behavior of these materials and thus enables a numerical analysis of the materialbehavior. The main goals of the research project include: • Identification of the influence of the forming history, the loading direction as well as the stress state on the formability and themechanical parameters of the selected materials. • Systematic differentiation and detection method for distinguishing between ductile failure and shear failure with adaptation of the time-dependent evaluation method. • Deriving a critical ratio between the pre-strain and a load direction change, from which on a shear failure occurs instead of necking which leads to a consequent loss of formability. • Determining the influence of a relieving step and the associated relaxation of the material between the forming operations on thefailure pattern.• The non-linear texture development has a significant influence on the formation of micropores. This effect, which has not yet been investigated, is to be examined in more detail within the scope of this project.