Three-dimensional visualization structural characteristics and performance of discontinuous coarse fiber bamboo nodes

Abstract

Bamboo nodes play a crucial role in ensuring the strength of hollow-structured bamboo, but compared with the internodes of unidirectional fiber structures, their structural which has discontinuous fiber characteristics are less understood. Here, we studied the structure-performance-fracture relationship between the internodes and nodes of bamboo. We examined the spatial heterogeneity of bamboo nodes through a three-dimensional reconstruction imaging strategy. We combined pendulum impact and high-speed photography with scanning electron microscopy to explore the regular fracture mechanism of bamboo nodes and compare it with internodes. An increase in slightly convex and ridged bamboo nodes occurred because there were thicker fiber bundles at the bamboo nodes. This caused fiber bundles to be deflected towards both sides instead of following a straight line. The bamboo nodes were more prone to regular fracture due to the discontinuous characteristics of fibers at bamboo nodes and the large void defects in the cross-section of node ridges, which destroyed the longitudinal continuity of thin-walled cells and fibers. In addition, under an impact, the main fracture mode of bamboo nodes was surface-penetrating fracture, and the main fracture modes between nodes included fiber pulling, fiber pulling out, and fiber bridging. This study provides a more in-depth understanding of bamboo and practical guidance for its development and applications in engineering structure.