Helical EMG application for aluminum rheology studies

Abstract

To study the peculiarities of initiation, evolution and recollection of spall-type damage under axis-symmetric convergence using the impact method, the test bench with an explosive magnetic pulsed power source (EPPS) on the basis of a helical generator with an explosive opening switch and a current interrupter has been created. The EPPS allows shaping the trapezoidal current pulses with the amplitude from 4 MA to 12 MA, full base duration from 10 to 250 μs and front rise duration ~ 2 μs in the load (liner). The magnetic field produced by the EMG current ensures the isentropic drive of a cylindrical liner used to create a shock wave of the required characteristics in the targets. In experiments “R-Damage-8,9” representing the completion stage of the experimental series “R-Damage-0-9” realized jointly by the VNIIEF and LANL teams we used the isentropically driven liners to realize a set of processes of shock-wave compression, evolution of damage and recollection of a damaged matter under axis-symmetric convergence in the extruded aluminum. The features of these processes were recorded with the use of PDV technique due to the time dependencies of the hollow targets' inner surface velocity. The presented method allowed apparently for the first time realizing the full and incomplete recollection of the main crack as the results of metallographic analysis have showed. This result made it possible to verify the numerical models of the damaged medium recollection being developed at the present time.