Validation of a path-dependent constitutive model for FCC and BCC metals using "symmetric" Taylor impact

In this study, the rod-on-rod impact geometry was used at impact speeds of ca. 200 m s(-1). This is widely believed to be equivalent to the impact of a single rod on an infinitely rigid target and hence an ideal form of the T aylor test as no real target is infinitely rigid. However, our modelling st udies showed that the two rods do not behave symmetrically. Two metals were studied: AQ85 iron and XM copper. These were machined into cylinders 15mm long and 5.35mm in diameter. High-speed photographic sequences of the impac ts were taken with an interframe time of 5 mu s. These pictures were then d igitised to obtain profiles as a function of time. The bce material (iron) exhibited the classic 'mushroom' shaped profile which was relatively easy t o model as a function of time using existing constitutive models. However, the fee material (copper) exhibited an additional bulge a few millimetres f rom the impact face. This behaviour proved impossible to simulate using pat h-independent models. It proved, however, possible to simulate the behaviou r of fee copper in the 'symmetric' Taylor impact configuration using a newl y-developed path-dependent constitutive model. The paper contains the resul ts of this comparison between experiment, theory and modelling.