ABSTRACT
We propose a new material modeling approach for BCC metals, based on the addition of an internal state variable for modeling the strain rate history effects. The new internal state variable, r_ISV, has the dimensions of the strain rate and associates the material microstructural state at a given plastic strain to an equivalent state that would be produced by a constant strain rate test of magnitude r_ISV. The proposed formulation accounts for the strain rate history effects where the transients due to strain rate jumps are significant. The proposed concept is also applicable for modeling discontinuous yielding phenomena and peak forces during impact.