Project Details
Projekt
Development of a plane strain-test method for tubular semi-finished parts and a wide range of strain-rates
Subject Area
Primary Shaping and Reshaping Technology, Additive Manufacturing
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 464455227
Method planning for forming processes often uses simulation-based designs, which require detailed information about the elastic-plastic material behavior. Established basic tests and modelling approaches for finite element (FE) simulation exist for flat sheet metal semi-finished products, but the transfer to tubular semi-finished products is limited. Existing tests for the characterization of tubular semi-finished products (e.g. ring tensile test, tube burst test) have hardly been accepted in industrial practice, but existing material cards based on the testing of flat sheet metal products are mainly used. This results in a considerable error in the simulation of the following forming processes and the potential of a simulation-based process design is not fully exploited. Therefore, the aim of this research project is to develop a new method for material testing of tubular semi-finished products, which will compensate for the existing disadvantages of current testing methods.The process-oriented numerical modelling of material behavior requires material testing under the conditions that are characteristic for the regarded process. In the context of the forming of tubular semi-finished products, hydroforming is the dominating manufacturing process in addition to bending and preforming steps. For this technology the plane strain state and strain rates in the order of several 10/s are particularly relevant. The overall objective of the research project is therefore the development, trial and validation of a testing strategy for the material characterization of tubular semi-finished products under this strain state and at high strain rates. By applying the presented methodology, a much more exact modelling of the material behavior and thus a more precise numerical modelling of the forming of tubular semi-finished products becomes possible compared to the state of the art. An extensive and locally resolved characterization of the tubular semi-finished products allows an identification of the interrelations between lattice type, texture, stress state and strain rate sensitivity. Due to the resulting deeper understanding of the micromechanical processes in the material, a significant improvement of the model quality will result. The steel alloy C45 will be investigated as a simple (body-centered cubic) model material, which allows a clear understanding of the basic correlations. Subsequently, the test methodology is transferred to an austenitic (face-centered cubic) chrome-nickel steel (1.4301), which is used in the industrial context in the area of exhaust systems.
DFG Programme
Research Grants
Co-Investigators
Dr.-Ing. Sebastian Fritsch; Dr.-Ing. Sven Winter
