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Principle and setup for characterization of material parameters for high-speed forming and cutting

Prinzip und Aufbau zur Charakterisierung von Werkstoffkennwerten für das Hochgeschwindigkeitsumformen und -trennen
: Tulke, Marc; Scheffler, Christian; Psyk, Verena; Landgrebe, Dirk; Brosius, Alexander

Fulltext ()

Procedia Engineering 207 (2017), pp.2000-2005
ISSN: 1877-7058
International Conference on Technology of Plasticity (ICTP) <2017, Cambridge>
Conference Paper, Journal Article, Electronic Publication
Fraunhofer IWU ()
High strain rates; parameter identification; Material characterisation; sheet metal

Velocity effects in production technology provide technological and economic advantages, but at the same time they necessitate consideration of strain rate dependent material behavior in process modelling. This paper proposes an innovative approach for material characterization in terms of strain rate dependent flow curves and failure describing parameters. Two driving concepts for high velocity testing, which can be used for examining the material behavior under different load cases by considering different specimen geometries, are presented: a pneumatic one for plastic strain rates up to 1,000 s-1 and an electromagnetic one for strain rates of 5·102 s-1 up to 105 s-1. Compared to the Split-Hopkinson-Bar-Test normally used, there are some advantages regarding achievable strain rates and achieved measurement data. In principle, knowledge about the strain paths, stress paths and local distributions of stress and strain in the specimen is essential for identifying material characteristics. Short process times, fast changes of the measurement values, small specimen size and frequently limited accessibility of the specimen during the test hinder directly measuring these parameters at high velocity testing. Therefore, here auxiliary test parameters, which are easier to measure, are recorded and used as input data for an inverse numerical simulation that provides the desired material characteristics as a result. For a first evaluation of the test arrangement, the concept was investigated in a numerical sensitivity study and the measuring principle was verified experimentally in a drop tower test.