Dynamic fracture of copper under the action of a relativistic high-current electron beam

Abstract

This paper presents the results of investigations of the dynamic spall fracture of bulk (2-6 mm) copper targets under the action of a relativistic high-current electron beam (1.3 MeV electron energy, 50 ns pulse duration, ~10 10 W/cm 2 power density) generated by the SINUS-7 accelerator. By numerical simulation with the use of the BETAIN1 software package it has been found that the amplitude of the stress wave formed is 6 GPa and the deformation rate is 5⋅10 5 s -1 . As established experimentally, there is a practically linear relationship between the thickness of the target and the thickness of the spalled layer. Comparison of the experimental data and the simulation results has shown that the spall strength of copper under the given conditions is 1.3 GPa, which is in good agreement with the data available in the literature. Analysis performed with the use of fractographic teqniques has revealed that in the case of recrystallized copper the size of the spall pits formed inside the grains is four times greater than the size of the pits formed on the grain boundaries.

Deformation behavior and spall fracture of the Hadfield steel under shock-wave loading

“…According to estimates based on simulation of shock-wave dynamics for pure metals [10], a quasi-plane shock wave of compression with duration of ~0.2 μs and amplitude of ~20 GPa was formed in the specimen. Due to reflection of the shock wave from the free back surface, a tension wave was formed that caused rear spall of the specimen.…”

“…Due to reflection of the shock wave from the free back surface, a tension wave was formed that caused rear spall of the specimen. The strain rate was ~10 6 s -1 [10].…”

“…The thickness of the spall layer increased almost linearly from 0.4 to 0.6 mm when the target thickness increased from 1.5 to 4 mm. This dependence is characteristic of the spallation of metal targets exposed to shock waves generated by nanosecond laser [12] and electron beams [10,11]. This is due to the fact that the amplitude of the shock wave that reached the back target surface is attenuated stronger with increasing target thickness.…”

“…To form shock waves, nanosecond ion [9] and electron beams with energy density of 10 10 -10 11 W/cm 2 [10,11] are typically used together with high-speed plate impact.…”

Numerical modelling of physical processes and structural changes in metals under intensive irradiation with use of CRS code: dislocations, twinning, evaporation and stress waves

“…It combines numerical solution of the continuum mechanics equations and the transport of fast particles. This code was used for evaluation of stress fields inside the irradiated material [2] and thermodynamic conditions on its surface [3]. In spite of universality and embedded solution of transport problem, the simplest model of perfectly plastic body is used for shear stresses in the BETAIN code, as well as equilibrium approximation for the liquid-vapour transition.…”