Investigation of the deformability of ductile sheet metal materials under non-proportional loading, taking into account the anisotropic damage behavior

Prof. Michael Brünig, Professor of Structural Mechanics, has successfully applied for the DFG project "Untersuchung des Formveränderungsvermögens duktiler Blechwerkstoffe unter nichtproportionaler Belastung mit Berücksichtigung des anisotropen Schädigungsverhaltens" (Investigation of the deformability of ductile sheet metal materials under non-proportional loads, taking into account the anisotropic damage behavior).

Duration: 2021 - 2023
Sponsor: DFG research grant

Determining the deformability of sheet metal materials is an important step in the design of sheet metal components. Since complex components have a non-linear deformation history, a description using a linear forming limit curve is not sufficient, since the remaining forming capacity and the type of failure depend significantly on the deformation history. As part of this research project, it should be possible to predict the deformability after non-proportional expansion paths with a change in the direction of loading. Two materials, AA6xxx and DP600, are systematically examined for this purpose in order to gain insights into their deformability and their failure after complex deformation history. With the help of numerical simulations, a damage model is created which is intended to depict the deformation and failure behavior of these materials and thus enables a numerical analysis of the material behavior. The main goals of the research project include:

• Investigation of different materials under non-proportional strain paths with a change in the direction of loading.
• Identification of the influence of the forming history, the direction of loading and the state of stress on the formability and the mechanical parameters of the selected materials.
• Systematic differentiation and verification method to differentiate between necking failure and shearing failure with adaptation of the time-dependent evaluation method.
• Deriving a critical relationship between the pre-strain and a change in load direction, from which point shear failure occurs instead of necking failure with an associated loss of formability.
• Determination of the influence of a relief step and the associated relaxation of the Materials between the forming operations on the failure pattern.
• The non-linear texture development has a significant influence on the formation of micropores. This previously unexamined effect is to be examined more closely within the scope of this project.