Experimental Investigation and FE Modeling of the High Temperature Dynamic Properties of Metals in the Kolsky method

In a wide range of practical problem on the dynamic strength associated with the impact and penetration an adequate definition of the material properties as a strain rate and temperature function has a great importance. One of the most effective and reliable methods for determining materials properties at high strain rates is the Kolsky method using the split Hopkinson bar [1]. This method is based on the one-dimensional theory of elastic wave propagation and the assumption of homogeneity of strain in the sample. It allows to obtain the deformation diagram for the processes of compression and tension in the range of strain rates 200-10000 s-1. Two basic schemes of the initial heating of the sample exist to study the materials properties at elevated temperature. In the one case, the heater is located directly on the axis of the rods (Fig.1) and heat-exposed not only the sample but also the adjacent parts of the rods. In the second scheme, the furnace is at the distance from the rod (Fig. 2), heat is directly exposed to the sample. Thus, researcher should take into account a non-uniform temperature field produced by rapid cooling of the sample while delivering from the oven to the bars. In all cases it is necessary to clarify the standard scheme of the Kolsky method. The paper is concerned with a numerical and experimental investigation of the temperature and the stress-strain state in the specimen in compression tests with split Hopkinson bar with a remote oven. The goal was to determine the degree of heterogeneity of the temperature field in the sample during the test and to discuss the approaches to the refinement of a standard methodology.