DEVELOPMENT OF HIGH STRAIN RATE STANDARD SAMPLES FOR HOPKINSON DEVICE CALIBRATION

In order to conduct the Hopkinson device calibration work, a high strain rate calibration standard sample has been developed. Focusing on reducing the discreteness of test results under high strain rates, analysis has been conducted from three aspects: sample selection, external interface control, and internal grain refinement. Research has shown that low hardness pure copper materials are suitable for producing Hopkinson rod calibration standard samples. By strictly controlling sample parallelism and face friction, and using equal channel angular compression method for grain refinement, the standard samples produced have good consistency in experimental results at high strain rates. With the increase of strain rate, the grain size of pure copper shows an increasing trend. The pure copper standard samples under high strain rate are ultrafine grain structure, and the dispersion of test results is small, which can satisfy the requirements of Hopkinson device calibration work.