BUCKLING LIFE ESTIMATION OF CIRCULAR TUBES OF DIFFERENT MATERIALS UNDER CYCLIC BENDING

In this paper, the buckling life estimation of circular tubes of different materials subjected to cyclic bending is investigated. A tube-bending machine and a curvature-ovalization measurement apparatus were used to conduct the curvature-controlled cyclic bending test. Materials of the tested circular tubes include 304 stainless steel, 316L stainless steel, 70:30 brass, 7005-T53 aluminum alloy and Ti-2Al-Cb-Ta titanium alloy. The mechanical behavior (moment - curvature and ovalization - curvature relationships) and buckling life (relationship between the controlled curvature and number of cycles necessary to produce buckling) were constructed according to the experimental measured data. The endochronic theory combined with the principle of virtual work was used to simulate the mechanical behavior of circular tubes of different materials. In addition, a theoretical formulation was proposed for estimating the buckling life of circular tubes of different materials. It has been shown that the simulation results are in good agreement with the experimental data.