CONSTITUTIVE RELATIONS OF ANNEALED COPPER UNDER DYNAMIC LOADINGS

ABSTRACT Constitutive relation of annealed copper was investigated through the tests under different loading histories, which consist of jump, dynamic and dynamic reloading. The tests were performed on the stress bar method, where the dynamic stress-strain behavior was measured precisely in small strain range. A unique relationship was found between plastic strain rate and over stress from the jump tests. On the other hand the relations were not unique for dynamic and dynamic reloading tests that the curves were different from that of the jump test in the initial stage of dynamic deformation, but it became concurrent with the jump test. The behavior could be reasonably explained by the model of varying density of mobile dislocations in the thermal activation theory.