New testing techniques to obtain tensile stress-strain curves for a wide range of strain rates

摘要

A new method of applying a dynamic load directly to a tensile specimen was developed. By combining the new method with the testing method based on a sensing block [1-5], we improved the testing method to obtain the entire tensile stress-strain curves for a wide range of strain rates on the order of 10~(-3)～10~3 s~(-1), with remarkable accuracy, especially for the high strain rates range. Based on numerical simulations and experiments, the accurate of the measurement of the non-coaxial Hopkinson bar method [6, 7] was discussed. By performing a series of numerical simulations, the relation between the gauge length of a specimen and the testing strain rate, necessary for obtaining an accurate dynamic stress-strain curves corresponding to a testing error of approximately 2% or 4%, was also obtained for a wide range of strain rates from 10s~(-1) to 10~4s~(-1).