3D characterization of vascular bundle in moso bamboo node and its effect on compressive properties

The structure of the bamboo node obviously differs from that of the internode and largely affects the mechanical properties of bamboo. However, the node structure of moso bamboo, an important economic and ecologic bamboo species, was still unclear. Thus, in this study, the 3D structural changes of the vascular bundle (VB) in the moso bamboo node were visualized and quantified. The compressive properties and failure mechanisms of the bamboo node were discussed based on the structural changes. The results showed that the horizontal VB in bamboo node was classified into three types: branching, cross-linking, and thickening. The cross-sectional area of the vertical VB in bamboo node increased, and the vertical VBs shifted to the outer side after passing through the node. Due to the "wire hoop " effect of the horizontal VBs, the longitudinal compressive strength of the node was greater than that of the internode. The deflection of VBs caused slippage between VBs and resulted in the decrease of the node's transversal compressive strength. This research provided key information for a deeper understanding of the structure and mechanical properties of bamboo for potential applications.