Multiscale Analysis of Adiabatic Shear Bands in Tungsten Heavy Alloy Particulate Composites

We use a multiscale approach to analyze adiabatic shear bands in a tungsten heavy alloy particulate composite deformed in plane strain tension at a nominal strain rate of 5000/s. Fifty IJ.m diameter circular tungsten particulates are assumed to be randomly distributed and perfectly bonded to the nickel-iron matrix. The volume fraction of particulates equals 50%. We first analyze transient coupled thermomechanical deformations of a homogenized body with values of thermophysical material parameters equivalent to those of the particulate composite. Time histories of deformation variables on the bounding surfaces of the centrally located 2 mm x 2 mm subregion of the 10 mm x 10 mm region are recorded. Boundary conditions of surface tractions and temperature rather than of velocities and temperature are then used to analyze plane strain coupled thermomechanical deformations of the 2 mm x 2 mmcomposite in which tungsten particulates are randomly distributed in the central 1 mm x 1 mm subregion of the 2 mm x 2 mm region with the remaining part comprised of the equivalent homogeneous materiat of the 10 mm x 10 mm body. It is found that the multiscale analysis of the problem gives an adiabatic shear band initiation time of'"'"' 22 I.1S as compared to '"'"' 58 I.1S in the equivalent homogenized body and'"'"' 50 I.1S in the macroanalysis of deformations of the 1 mm x 1 mm region containing a randomly distributed 500;0 volume fraction of 50 IJ.m diameter tungsten