Effect of impedance mismatch on flier plate impact response of metal laminates

We use experiments and modeling to investigate the effect of elastic impedance mismatch on the response of layered metal composites to flier plate impact. We choose Cu/Ta and Cu/Nb laminates as model materials for their high and low impedance contrast, respectively, while many other properties (flow stress contrast, lattice misfit, etc.) are comparable. Using elastic finite element modeling, we predict that the minimum impact velocity needed to initiate spall depends on impedance contrast, with the critical velocity being lower in Cu/Ta than in Cu/Nb. We process samples by accumulated roll bonding (ARB) and examine their dynamic failure using flier plate testing. This investigation sheds light on the role of impedance contrast in shock propagation and attenuation and in the resulting failure mechanisms.