A constitutive modeling of creep stain for pure copper at room temperature

초록

In the electrical railway, a hard drawn pure copper is used as a wire, namely a contact wire, to supply electrical energy for a train through a pantograph. For a good current collection, the contact wire is always acted on a constant uniaxial tension. So, the efficient diminishment of the initial creep deformation under construction is important for the maintenance of electrical railway. The entire history of tensional loading is essential to know the present state of deformation [1]. Kowalewski [2] studied on the influence of plastically pre-deformed pure copper on the creep at elevated temperature, and found a hardening effect during creep in case of plastic pre-strained pure copper comparing with non pre-strained one. And many researches for the creep behavior in high temperature are performed with pure materials [3, 4]. In my previous work [5], the effect of elastically pre-deformation for a hard drawn pure copper at room temperature was studied. In that paper, the test results of creep transients associated with stress reductions were analyzed. After the stress of 218MPa and 164MPa are applied for 0.5 hours for each specimen, and then the creep behavior were examined under the stress of 109MPa at room temperature. In this paper, the modified constitutive modeling of stain rate for pure copper under a constant tension considering a history of tensional loading is presented and compared with the experiment results.