Studying the Dynamic Strain of Copper and Its Alloy by the Split Hopkinson Bar Method

The study is undertaken in order to obtain experimental data on dynamic compression of structural materials for refining computational models that describe material behavior under dynamic loading. The task was to study the dynamic properties of a copper-tin alloy and copper MOOK in the strain rate range (epsilon) over dot = 102 10(4) s(-1). The problem of strength and failure under a single intense loading, such as shock, explosion, etc. occupies a special place in the general problem of the strength of materials and structures under dynamic loading. High strain rates or shock loading, high stress levels, high plastic strain predominantly in the isentropic process of deformation, and specific behavior of the material under such loading cause difficulties in experimental studies forming a basis for physical and mathematical models of material strain and failure that are used in structural calculations. The possibility of comparing the results of the studies and their reliability are primarily determined by the scientific validation of the setup of high-rate material tests. One of the methods having a clear theoretical basis, high efficiency, generality and reliability of the obtained results is the split Hopkinson bar (SHB) method, or the Kolsky method. This method allows one to study dynamic diagrams of compression and tension at strain rates (epsilon) over dot = 10(2) 10(4) s(-1). The paper contains the experimental results of tests on dynamic compression of copper and a copper-tin alloy performed by the SHB method. The diagrams of dynamic compression have been determined. The strain model parameters for copper and its alloy have been obtained in Johnson-Cook form widely used in dynamic calculations.