Deep drawing with additional force transmission

• Applicant: Professor Dr.-Ing. Bernd-Arno Behrens
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: from 2012 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 212270168

The material-specific process limits during deep drawing depend on the stress distribution in the workpiece. If the load limit of the material in a certain region of the workpiece is exceeded, then the material failure occurs. By locally activating an additional force transmission during deep drawing, the sheet metal material can be relieved in the critical areas for crack entry and the process limits can be extended. Here, the finite element method for numerically predicting the achievable process window in terms of component failure is an indispensable tool.The aim of the follow-up project is to determine the deformability of sheet steels HCT600 and HX340 (both s0 = 1.0 mm) in a wider range of strain states (from sheer up to equibiaxial pressure) compared to forming limit curve (FLC) and to integrate it into FE simulation of the conventional deep-drawing process as well as deep drawing with additional force transmission in the form of a suitable stress-based failure model. Here the influence of the process-induced stress state on the deformability is to be determined experimentally. Within the material characterization the formability of HCT600 and HX340 in consideration of different stress state will be determined. The shear tensile test set-up developed at the IFUM enables plastic deformation to be located in the middle of the stress region of the test specimen, regardless of sample orientation and stress state. Subsequently, a stress-based failure criterion will be generated. This will be verified with respect to the numerical prediction of material failure during deep drawing with the activation of an additional force transmission. By failure modeling, the surface pressure, loaded on the material in a certain stage of the deep-drawing process, will be also taken into account.The project results should contribute to the accuracy of the simulation-based design of conventional sheet metal forming processes as well as the processes with additional force transmission with regard to the use of high-strength sheet steel materials.

• DFG Programme: Research Grants