Cyclic creep of copper due to axial cyclic and tensile mean stresses

The behaviour of materials under axial stress-controlled cycling with tensile mean stress within the plastic region is governed by a superposition of cyclic creep and fatigue processes. Cyclic creep may dominate the damage process and cause distortional failure before the onset of fatigue cracking. The aim of this work was to investigate cyclic creep in copper under such loading conditions at room temperatures, and to derive an empirical relationship for cyclic creep in terms of imposed stress amplitude and mean stress, via a previously proposed exponential mean-stress function that accounts for the effect of mean stress on cyclic behaviour. It is found that cyclic creep behaviour at room temperatures could be described by a power-law relation similar to that of static creep at high temperatures.