Dynamic Constitutive Model and Deformation Mechanism of 2219 Aluminum Alloy Based on the Dynamic Interruption Recovery

摘要

Dynamic compression and interruption-recovery experiments are carried out to investigate the dynamic adiabatic and isothermal deformation behavior of the 2219 aluminum alloy at various strain rates (0.001-5000 s-1). The results of the experiments show that adiabatic temperature increase and strain rates have an impact on the compression behavior of 2219 aluminum alloy. The yield strength is strongly associated with strain rates, demonstrating an evident strain rate hardening effect. The increase in adiabatic temperature is the key factor contributing to the decline in adiabatic strain hardening rate. According to microstructural analysis, the adiabatic shear band is first detected with strain rate of 3200 s-1 along the loading direction. At a strain of 30.3%, cracks begin to appear, and shearing fractures occur with a strain rate of 5000 s-1 in the direction of 45 degrees. Finally, the Johnson-Cook constitutive model is modified with the strain rate reinforcement terms corrected and an adiabatic softening term added to reflect the isothermal and adiabatic compression behaviors. The improved model is better at describing the strain rates affect the behavior of isothermal and adiabatic deformation. @@@ Dynamic compression and interruption-recovery tests are conducted using a Split-Hopkinson compression bar to obtain the adiabatic and isothermal stress-strain responses of the alloy at high strain rates. The Johnson-Cook constitutive model is modified by correcting the terms of strain rate reinforcement and introducing an adiabatic softening term to describe the isothermal and adiabatic compression behavior.

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