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 exper imental technique has been developed to obtain the isothermal stress-s train relations of materials under high strain rates. The thermal soft ening effect can be decoupled by comparing the isothermal stress-strai n relations with the adiabatic stress-strain relations at the same str ain rate. In the present paper, recovery experiments of brass have bee n carried out on a self-designed rotating disk tensile impact apparatu s. According to the parabolic strain hardening power-law thermoviscopl astic constitutive model, strain hardening parameter, strain-rate stre ngthening parameter and thermal softening parameter have been decouple d from experimental results. Furthermore, from these parameters, one c an 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 tensile impact recovery experimenta l technique is effective and reliable, and is an important means for t he study of thermomechanical coupling. The experimental results also r eveal that brass is a typical thermoviscoplastic material.