Abstract
In order to investigate the dynamic deformation behaviour of annealed polycrystalline aluminium at room temperature, its dynamic stress-strain curves at high strain rates (102∼104 sec−1) were obtained using a bar-bar type impulsive loading apparatus. In this experiment, a cylindrical specimen was inserted between two elastic bars and compressed rapidly by transmitting a stress pulse generated by the impact of a bar.
The dynamic stress-strain curve is parabolic in a way similar to the static curve. The dynamic flow stress is always higher than the static one showing strain rate dependence. From the results obtained at higher strain rates the stress-strain-strain rate relationship is summarized by an equation
σ(kg⁄mm2)=12.8·ε0.38·\dotε1⁄16(sec−1).
It is concluded from the results that the flow stress depends not only on the instantaneous strain and strain rate but also on the strain rate history of the specimen.
