Material characterisation and constitutive modelling of a tungsten-sintered alloy for a wide range of strain rates

The behaviour of a tungsten-sintered alloy has been investigated using a combination of tension tests, modified Taylor-impact tests and planar-plate-impact (PPI) tests using the VISAR technique. A logarithmic yield stress-strain rate dependency as it is predicted by the original Johnson-Cook (JC) strength model covering a strain rate range of 10 orders of magnitude has been measured. With the PPI tests the Hugoniot elastic limit and the spall strength, as well as the U-s-u(p). relation have been determined. Model parameters for the JC strength model and an equation of state have been determined from the experimental results. The validation of the material model has been performed by numerical simulations of the modified Taylor-impact tests where an enhanced model validation has been done by comparing the measured and calculated VISAR signals while this technique is normally used for PPI tests only. (C) 2008 Elsevier Ltd. All rights reserved.