The effect of mean curvature on the response and collapse of thin-walled tubes under cyclic bending

This paper presents the experimental and theoretical results of the effect of mean curvature on the response and collapse of thin-walled tubes subjected to cyclic bending. To highlight the influence of mean curvature effect, three different curvature ratios (minimum curvature/maximum curvature) were experimentally investigated in this study. It was found that the response and collapse of thin-walled tubes subjected to cyclic bending are strongly influenced by the magnitude of the mean curvature. In addition, the ordinary differential constitutive equations of endochronic theory were used to investigate the response of thin-walled tube subjected to cyclic bending. Furthermore, a theoretical formulation was proposed so that it can be used for simulating the relationship among the controlled curvature range, curvature ratio and the number of cycles to produce buckling for thin-walled tubes subjected to cyclic bending. The theoretical simulations were compared with the experimental tested data. Good agreement between the experimental and theoretical results has been achieved.