Identification of strain-rate-dependent hardening model for aluminium alloy sheet in electromagnetic forming

The deformation rate of aluminium alloy sheet reaches up to thousands per second in the electromagnetic forming process, and how to obtain the hardening behaviour of aluminium alloy sheet at such high strain rate becomes an essential issue. The electromagnetic hole-flanging test is proposed to simplify the deformation process. Based on the electromagnetic hole-flanging test, the inverse identification procedures are adopted to calibrate the strain-rate-dependent hardening models of aluminium alloy sheet. For the Johnson-Cook and Cowper-Symonds hardening models, the strain-hardening terms were initially determined by the quasi-static uniaxial tensile tests to simplify the inverse procedures. Then, the strain-rate-dependent terms were identified by comparing the simulated and experimental strains of the electromagnetic hole-flanging test. It was validated to calibrate the Johnson-Cook and Cowper-Symonds models of AA5754 aluminium alloy sheet by combining the electromagnetic hole-flanging test with the quasi-static tensile test.