Bamboo mechanics

Abstract

Bamboo, as one of the most renewable biological materials, has recently received increased research interests for sustainable structural applications. Despite their superior mechanical strength and toughness, the underling mechanisms for their fracture properties were less understood. In this work, we systematically studied the mechanics of structural bamboo materials by using multi-scale mechanical characterization coupled with environmental scanning electron microscopy (ESEM) and in situ dynamic testing. We firstly revealed that, upon bamboo fracture, the fibers' interfacial areas along with parenchyma cells' boundaries are preferred routes for crack growth in bamboo's radial and longitudinal directions. We then studied the asymmetric flexural behavior of structural bamboo materials due to the functionally gradient distribution of vascular bundles, whereas the hierarchical fiber/parenchyma cellular structure plays a critical role in alternating the distinctly different failure modes. Lastly, we investigated the viscoelastic behavior of desiccated bamboo with respect to its molecular building blocks, with the assist of molecular dynamics (MD) simulations. Our case study on bamboo mechanics may offer a unique perspective toward better understanding the mechanical properties and fracture mechanisms of hierarchical biomaterials and help the design of bio-inspired, functionally graded composite structures.