Effect of Strain Rate on the Propagation of a Plastic Strain Pulse Along a Lead Bar

Tests have been carried out to determine how pulses of plastic deformation disperse during propagation along a lead bar. Step function loading was employed in order to avoid complications resulting from the presence of relief stresses. By using a double pressure step technique, it was shown that the dispersion cannot be due solely to the nonlinearity of a time-independent stress-strain relation. On the other hand even a very simple model of a metal exhibiting a strain-rate effect serves to predict qualitatively all of the main features of the experimental observations. It is therefore concluded that in the case of lead a strain-rate effect plays an important part in controlling the behavior of a plastic strain pulse.