Characterization of dynamic hardening behavior at intermediate strain rates using the virtual fields method

Abstract

Crash analysis simulation is now very important in automotive industry to assess automotive crashworthiness and safety. In order to acquire reliable crash simulation results, precise material behaviors at intermediate strain rates should be used as input data. To derive the stress-strain curves at various strain rates, a large number of experiments are needed, which is costly and time consuming. The present study aims at determining the stress-strain curves of sheet metals at various strain rates from a single dynamic experiment. A new type of high-speed tensile tester for sheet metal specimens was built and high-speed tensile tests were carried out. Full-field heterogeneous strain fields were measured by a digital image correlation technique using a high-speed camera. The load data was acquired from strain gauges attached to the elastic deformation region on the specimen. Then, an inverse identification scheme with a rate dependent hardening law was applied to retrieve dynamic parameters. The stress-strain curves of three advanced high strength steels at intermediate strain rates (100 s−1 – 300 s−1) were successfully obtained from a single experiment.