2014 Volume 1 Issue 2 Pages SMM0005
In this paper, the response of sharp-notched circular tubes with notch depths of 0.2, 0.4, 0.6, 0.8 and 1.0 mm subjected to bending creep and relaxation are investigated. The bending creep or relaxation is to bend the tube to a desired moment or curvature and hold that moment or curvature constant for a period of time. From the experimental result of bending creep, the creep curvature and ovalization increase with time. In addition, higher held moment leads to the higher creep curvature and ovalization of the tube's cross-section. From the experimental result for bending relaxation, the bending moment rapidly decreases with time and becomes a steady value. As for the ovalization, the amount increases a little with time and gradually becomes a steady value. Due to the constant ovalization caused by the constant curvature under bending relaxation, the tube does not buckle. Finally, the formulation proposed by Lee and Pan (2002) is modified for simulating both the creep curvature–time relationship in the first stage under bending creep and the relaxation moment-time relationship under bending relaxation for sharp-notched circular tubes with different notch depths. Through comparing with the experimental finding, the theoretical analysis can reasonably describe the experimental result.
