Three-point bending of thin-walled rectangular section tubes with indentation mode

The local indentation and bending collapse are two typical energy dissipation mechanisms of thin-walled tubes under lateral impacts. These two mechanisms are always developed simultaneously for tubes under three-point bending, but there are still few studies concerned with this phenomenon. This paper addresses the indentation mode of thin-walled tubes under three-point bending. Quasi-static experimental tests are conducted first for square tubes with particular dimensions, and the nonlinear finite element code LS-DYNA is then used to simulate the tests. Parametrical studies are conducted to analyze the influence of geometrical parameters on deformed shapes and force response. Results show that the span, wall thickness and punch diameter have significant influence on the response of tubes, while the sectional width has a small influence. On the basis of the analysis of energy dissipation mechanisms, a theoretical model is proposed to predict the force response of thin-walled tubes. Ideal rigid perfectly-plastic material assumption and the dimensional analysis method are employed to help derive the force-displacement characteristics. Finally, the theoretical predictions are validated by experiments and simulation results of thin-walled rectangular tubes with a wide range of geometric parameters.