The mechanical behavior and buckling failure of sharp-notched 6061-T6 aluminum alloy tubes with different notch depths subjected to cyclic bending are experimentally and theoretically investigated. The experimental moment–curvature relationship exhibits an almost steady loop from the beginning of the first cycle. However, the ovalization–curvature relationship exhibits a symmetrical, increasing, and ratcheting behavior as the number of cycles increases. The six groups of tubes tested have different notch depths, from which two different trends can be observed from the relationship between the controlled curvature and the number of cycles required to ignite buckling. Finite element software ANSYS is used to simulate the moment–curvature and ovalization–curvature relationships. Additionally, a theoretical model is proposed for simulation of the controlled curvature-number of cycles concerning the initiation of buckling. Simulation results are compared with experimental test data, which shows generally good agreement.

In this paper, the finite element software ANSYS Workbench 14.0 is used to analyze the moment-curvature and ovalization-curvature relationships of 6061-T6 aluminum alloy tubes with a local sharp cut under curvature-controlled symmetrical cyclic bending. The cut depths of 0.4, 0.8, 1.2, 1.6 and 2.0 mm were considered. The experimental moment-curvature relationship exhibited an almost steady loop from the beginning of the first cycle; the cut depth had almost no influence on the curves. Moreover, the ovalization-curvature curve increased in an increasing, unsymmetrical and ratcheting manner with the number of bending cycles. Large cut depths resulted in larger ovalization of the tube cross-section. The ANSYS analysis was compared with the experimental finding. The simulated results exhibited close correspondence to those obtained from the experiments.

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