Local loading conditions associated with shear banding formation in laboratory -@ten alloy specimens are examined. The specimens consist of compression specimens of large length to diameter ratio made of 91W-6Ni-3Co swaged tungsten alloys tested with the Hopkinson pressure bar and symmetric Taylor techniques. Experimental and numerical results provide insights on the effect of the hydrostatic p...

354 Abstract We study thermomechanical deformations of a viscoplastic body deformed in plane strain compression at a nominal strain-rate of 5000 sec~. We develop a material model in which the second order gradients of the velocity field are also included as kinematic variables and propose constitutive relations for the corresponding higher order stresses. This introduces a material characterist...

We present an efficient two-band k·p theory which accurately describes the six lowest conduction band valleys in silicon. By comparing the model with full band pseudo-potential calculations we demonstrate that the model captures both the nonparabolicty effects and the stress-induced band structure modification for general stress conditions. It reproduces the stress dependence of the effective m...

Marchand and Duffy tested thin-walled steel tubes in a split Hopkinson torsion bar at a nominal strain-rate of approximately 1600/s and could not determine conclusively whether a shear band initiating at a point in the tube propagated around the circumference in one direction or in both directions. They estimated the speed of propagation to be 520 m/s in the former case and 260 m/s in the latte...

The ductility and plastic flow behavior of highly aligned nanotwinned copper produced by interrupted magnetron sputtering is investigated. Tensile tests were performed at various strain rates at both room and liquid nitrogen (77 K) temperatures. Higher ductility and strength are reported for all samples tested at 77 K. The observed inhomogeneous deformation and shear band propagation are discus...