Constitutive model and forming limit prediction of AA5182-O aluminium alloy sheet in electromagnetic forming

Based on the electromagnetic hole-flanging (EMHF) experiment and numerical simulation, the inverse identifications of Johnson-Cook (J-C), Huh-Kang (H-K), Allen-Rule-Jones (A-R-J) and Cowper-Symonds (C-S) constitutive models were performed for AA5182-O aluminium alloy sheet at high strain rates. The accuracy of constitutive models was inspected by comparing the simulated height and thickness with experimental ones. The flow stress curves of AA5182-O aluminium alloy sheet at high strain rates were investigated. Based on the Marciniak-Kuczynski (M-K) model and constitutive models, the electromagnetic forming limit curves (EMFLC) of AA5182-O aluminium alloy sheet were predicted. The results show that the constitutive models at high strain rates can be determined by inverse identification on basis of EMHF. The flow stress curves at high strain rates predicted by different constitutive models are significantly distinguished. The constitutive model directly affects the numerical prediction of EMFLC. The EMFLC with J-C and A-R-J models shows little strain rate sensitivity, the EMFLC with H-K model shows positive strain rate sensitivity at a certain range of strain rate, and the EMFLC with C-S model shows significantly positive strain rate sensitivity.