The modified Johnson-Cook constitutive model of 2A10 aluminum alloys under electromagnetic impact loading

The dynamic response description of materials in high-speed impact fields is of practical significance to structural design and practical engineering application. In this paper, an electromagnetic impact (EI) loading process was proposed to acquire dynamic stress-strain relationships of 2A10 aluminum alloys. A modified Johnson-Cook (J-C) material model was obtained by combining with Quasi-static experiments and verified by numerical simulations. Comparing the J-C model obtained by a Split Hopkinson pressure bar, the simulative results about maximum deformation displacements showed the modified J-C model was more in line with actual experimental results. The accuracy under the discharge energy of 4 and 5 kJ was improved by 50% and 11%, respectively. In addition, electromagnetic impact loading characteristics and microstructure evolution of materials were studied. The discharge current with an attenuated sine wave caused that electromagnetic impact forces demonstrated a bimodal trend. The maximum impact velocities reached up to 4.7 m/s and 6.7 m/s under the discharge energy of 4 and 5 kJ, respectively (the maximum strain rates are 655.0 and 932.3 s −1 , respectively). The high-speed impact effect led to the emergence of adiabatic shear bands (ASBs) during deformation microstructure evolution. Due to higher impact speed, the deformation concentration degree was more remarkable under the energy of 5 kJ.