Volume 25, Issue 4 (July 1997)
A Constitutive Model for Metals at High Strain Rates Accurately Determined by the Tensile Impact Recovery Experimental Technique
Based on the loading-unloading test, the tensile impact recovery experimental technique has been developed to obtain the isothermal stress-strain relations of materials under high strain rates. The thermal softening effect can be decoupled by comparing the isothermal stress-strain relations with the adiabatic stress-strain relations at the same strain rate. In the present paper, recovery experiments of brass have been carried out on a self-designed rotating disk tensile impact apparatus. According to the parabolic strain hardening power-law thermoviscoplastic constitutive model, strain hardening parameter, strain-rate strengthening parameter and thermal softening parameter have been decoupled from experimental results. Furthermore, from these parameters, one can determine the theoretical isothermal curves and adiabatic curves at high strain rates, showing a good match with the experimental results respectively. This shows that the teasile impact recovery experimental technique is effective and reliable, and is an important means for the study of thermomechanical coupling. The experimental results also reveal that brass is a typical thermoviscoplastic material.