The Direct Impact Method for Studying Dynamic Behavior of Viscoplastic Materials

This work is devoted to the direct impact method for determining the deformation diagrams of viscoplastic materials at high strain rates. As the conventional Split Hopkinson Pressure Bar method, the direct impact method is based on the measuring bar technique. The description of the experimental scheme and the traditional experimental data proceeding method are given. The description and the results of numerical analysis of the direct impact scheme are presented. A modified procedure for processing experimental information is proposed which allows to expand the area of correct calculation of strains in the specimen according to the experimental data obtained by the direct impact method. As an illustration the deformation diagrams of copper S101 and aluminum alloy D16T in the strain rate range from 1000 to 10000 s^-1 have been obtained using the Split Hopkinson Pressure Bar method and the direct impact method. The use of the direct impact method made it possible to obtain deformation curves at strain rates an order of magnitude higher than the conventional SHPB method. The range of studied plastic deformations is increased by 4 times for the case of copper and 3 times for aluminum alloy.