Dynamic modeling and optimal design of Tube-Diaphragm coupling beam inspired by bamboo

摘要

Organisms in nature can inspire human research and design. Bamboo is generally acknowledged to be the structure with the best specific energy absorption and specific stiffness in nature. Compared to trees, it is difficult to break bamboo at its root and cause it to fall under dynamic loads, which can provide a useful reference for researchers. In this paper, a tube-diaphragm coupling beam inspired by bamboo was designed. The dynamic model of the bending vibrations of was established for the first time, and the influences of the structural parameters, such as the number of diaphragms, the tube thickness, and the impact pulse width on the impact characteristics of the tube-diaphragm coupling beams under transverse impact forces were analyzed. An optimal design of the tube-diaphragm coupling beams was obtained by particle swarm optimization. Specimens of bionic, solid, and hollow beams were prepared by the SLA (stereo lithography apparatus) 3D printing technology, and impact tests were carried out. The results of impact tests showed that the base vibrations of the solid and hollow beams were greater than those of the tube-diaphragm coupling beam for different impact pulse widths. The results indicated that bamboo can change its natural frequencies by adjusting the number of diaphragms and the tube thickness to adapt to changes of the environment. This adjustment can make the tube-diaphragm coupling beam absorb more energy through deformation, and thus, the dynamic force of the tube-diaphragm coupling beam at its root was smaller than those of solid and hollow beams. The results reveal the mechanism that allows bamboo to be difficult to beak at the root and fall, which can provide a useful reference for the design of beams and rotors.