The instability and localization of plastic shear at various imposed rates was considered. A wide range (50 to 100000/s) of nominal shear strain rates was studied numerically. A layer with a small geometrical defect was assumed, whose dimensions were exactly the same as those of the double shear specimen which was used in impact loading. A one-dimensional model for simple shear deformation was applied, together with complete constitutive relationships which were based upon structural evolution and dislocation kinetics. Constitutive modelling based upon dislocation dynamics was limited to body-centered cubic structures. The complete thermal coupling of plastic deformation was taken into account by using an exact Debye model for the specific heat. Thermal conductivity was accounted for in the numerical analysis. It was found that a critical nominal strain rate existed at which the formation of an adiabatic shear band was easiest. At very high (1000000/s) nominal strain rates, the increase in temperature within the band was found to be close to the melting point. The thickness of the adiabatic shear band was smallest for nominal strain rates of the order of 1000/s.

A Numerical Study of Adiabatic Shear Banding in Mild Steel by Dislocation Mechanics Based Constitutive Relations. J.R.Klepaczko, B.Rezaig: Mechanics of Materials, 1996, 24, 125-39