Mesoscale Analysis of Shear Bands in High Strain Rate Deformations of Tungsten/Nickel-Iron Composites.

We analyze the initiation and propagation of adiabatic shear bands in a tungsten heavy alloy by modeling each constituent as a heat-conducting, microporous, isotropic, elastothermoviscoplastic material. The two constituents are assumed to be perfectly bonded to each other so that the temperature, heat flux, displacements, and surface tractions are continuous across an interface between a tungsten particulate and the nickel-iron matrix. Three different modes of deformation, namely plane strain tension/compression, plane strain shear, and axisymmetric tension/compression are analyzed. No other defects are introduced. It is found that contours of the rate of temperature rise and/or velocity and/or the specific energy dissipation rate rather than those of effective plastic strain delineate the shear banded regions. For the same volume fraction of particulates smaller diameter particulates enhance the formation of adiabatic shear bands. The time of initiation of an adiabatic shear band also depends upon the particulate arrangement. [ABSTRACT FROM AUTHOR]