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

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 $10^{-3}\sim 10^{-3}$ s$^{-1}$, with remarkable accuracy, especially for the high strain rates range. Based on numerical simulations and experiments, the accuracy 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 approxmatety 2% or 4%, was also obtained for a wide range of strain ratesfrom 10$^{-1}$ to 10$^{4}$ s$^{-1}$.