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

Crash analysis simulation is now very important in automotive industry to assess automotivecrashworthiness and safety. In order to acquire reliable crash simulation results, precise materialbehaviors at intermediate strain rates should be used as input data. To derive the stress-strain curves atvarious 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 ratesfrom a single dynamic experiment. A new type of high-speed tensile tester for sheet metal specimenswas built and high-speed tensile tests were carried out. Full-field heterogeneous strain fields weremeasured by a digital image correlation technique using a high-speed camera. The load data wasacquired from strain gauges attached to the elastic deformation region on the specimen. Then, an inverseidentification 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.