Bending collapse of multi-cell tubes

Due to excellent energy absorption efficiency under bending collapse, multi-cell beams are extensively used as the components of protection structures. However, the theoretical prediction of their responses is still an unsolved problem. In this paper, two methods: dimensionless analysis method and energy analysis method are employed to derive the bending moment response of multi-cell tubes. Numerical simulations of double-cell tubes with different section dimensions are conducted first. The dimensionless analysis method is then employed to correlate the bending moment of double-cell tubes with the ratio of width to thickness b/t, the flow stress and the bending rotation angle. Based on Kecman's model, a theoretical model of double-cell tubes is presented and the bending moment response is derived according to the energy equilibrium of the system. Finally, the expression of a rolling radius of plastic hinge lines in the energy analysis method is determined to bridge the two methods. A comparison shows that the predictions provided by the present two methods agree well with the numerical results. Quadruple-cell tubes are also employed to validate the present methods and results show that the present methods are applicable for multi-cell tubes with other cross-sections. (C) 2017 Elsevier Ltd. All rights reserved.