Dynamic fracture under impact and high-strain-rate loading

A constitutive model based on a pressure-dependent yield criterion is used to predict damage evolution and ductile fracture under dynamic loading conditions. The model predicts the influence of porosity on plastic flow in metals and the nucleation, growth, and coalescence of internal microvoids to cause ductile fracture. The constitutive equations have been implemented in the DYNA2D finite-element code and have been used to simulate three high-strain-rate experiments: (i) the symmetric Taylor cylinder impact, (ii) the plate impact, and (iii) the tensile split Hopkinson bar experiments. In each case, the model is shown to capture qualitatively the damage and fracture within the experiments modelled. Comparison with recent symmetric Taylor impact experiments on leaded brass suggests that the model over-predicts the rate of damage evolution under the high-strain rate, high-triaxiality conditions associated with impact.