Dislocation based high-rate plasticity model and its application to plate-impact and ultra short electron irradiation simulations

This paper focuses on the development of a plasticity model to describe high rate deformations of metals. Modeling of target mechanical response is performed in frames of continuum mechanics. Plastic flow is described as the result of an over barrier dislocation sliding in specific slip planes. Computations of shock wave propagation in fcc, bcc and hcp metals modeling in comparison with shock wave experiments are performed to verify the model. The model predicts yield strength increase on elastic precursor in aluminum monocrystal and titanium of high purity at high temperatures. The action on a copper target of the electron beams with energy density (the total energy incident on an unit area during an irradiation pulse) 8.6J cm(-2) and varied pulse duration has been investigated. At the considered irradiation regime the target remains in a solid state (maximal temperature is 710 K) and shear stresses can reach values of about 0.72 GPa. Depth distribution of dislocation density after irradiation has a maximum that is localized on a distance of 10 mu m from the irradiated surface and the maximum dislocation density is about 6 x 10(9) cm(-2) in the target. The shortening of the exposure time to 1 ns leads to the increase of the dislocation density. Further reduction of exposure time has a weak effect on the dislocation density because the shear stresses reach a limit. (C) 2011 Elsevier Ltd. All rights reserved.