THERMOMECHANICAL REPRESENTATION OF ADIABATIC SHEAR BANDING

Abstract

A finite element method with a weak embedded discontinuity is implemented with a global tracking strategy to track the evolution of adiabatic shear bands in metallic materials. The continuum model used is developed with a thermodynamically consistent framework in which dislocation-based plasticity and dynamic recrystallization are used to model the softening and hardening mechanics of the material. Inclusion of an evolving adiabatic shear band calculation allows for minimal prescribed conditions. The computational framework implemented on a top- hat geometry is compared with Split-Hopkinson pressure bar results of 316L stainless steel and shows exceptional agreement, providing key insight into the deformation mechanisms in high strength steels and the usefulness of dynamic recrystallization as an additional softening mechanism. A Rolled Homogeneous Alloyed (RHA) steel was used for compression tests at both quasi-static loading conditions and dynamic loading conditions via a Split-Hopkinson Pressure Bar. Results of the experimental work will be used to parameter fit the plasticity and computational model in aims of simulating the dynamic compression of a top-hat sample of RHA material. The initial experimental results for RHA show little strain-hardening, and strain-rate sensitivity. There is a more prevalent temperature-sensitivity to the material, and softening has been observed in both quasi-static and dynamic loading conditions. The experimental finding for the compression of a top-hat sample of RHA material show an almost immediate softening of the material suggesting that the onset of strain localization occurs rapidly at the onset of yield.