Cyclic bending ovalization and critical ovalization of round-hole tubes

Abstract

This paper presents an experiment for examining the ovalization of roundhole 7075-O aluminum alloy tubes submitted to cyclic bending. Here round-hole diameters of 2 to 10 mm were considered. It can be seen that the ovalization-curvature relationships demonstrated an asymmetrical, ratcheting, increasing and bow trend with the increase in the number of bending cycles. The hole diameter revealed a dramatic effect to this relationship. Furthermore, higher hole diameters led to larger tube's ovalizations. Although five groups of round-hole 7075-O aluminum alloy tubes tested, the critical ovalization-controlled curvature relationships on a log-log scale exhibited nonparallel straight lines. Finally, a theoretical model was proposed for simulating the aforementioned relationships. The simulation results were compared with experimental test data, which showed generally good agreement.