The use of symmetric Taylor impact to validate constitutive models for an fcc metal (copper) and a bcc alloy (RHA steel) L.C. Forde, S.M. Walley, M. Peyton-Jones, W.G. Proud, I.G. Cullis and P.D. Church Published online: 15 September 2009 DOI: 10.1051/dymat/2009175