Rate Dependence of Structure Evolution in Copper and Its Influence on the Stress-Strain Behavior at Very High Strain Rates

摘要

A model for the deformation of copper over a wide range of strain rates has been modified to account for the contribution of dislocation drag at high strain rates. The main effect of adding this mechanism is found in the near yield region at strain rates exceeding 10 sup 3 s sup -1 . However, even at strain rates as high as 10 sup 6 s sup -1 the rate controlling deformation mechanism at strains greater than roughly epsilon=0.1 is thermal activation. It is postulated that the high stresses predicted at yield when the strain rates are raised above 10 sup 3 s sup -1 may lead to the rapid dislocation accumulation rates that have been found experimentally and which lead to the increased strain-rate sensitivity reported to copper and other metals at these strain rates. (ERA citation 12:035142)