Under static load, the idealized uniaxial stressestrain relationship
of mild steel (as shown in Fig. 2) is used to represent the
elastic-perfectly plastic behavior of steel. As the yield stress of steel
under dynamic loading is sensitive to strain rate [20], the dynamic
flow stress of steel increases with an increase of strain rate. The
CowpereSymonds constitutive equation is used here to simulate
the strain-rate sensitive behavior of steel under impact loading. The
CowpereSymonds constitutive equation is expressed as follow: