The structure and mechanics of Moso bamboo material

Abstract

Although bamboo has been used structurally for millennia, there is currently increasing interest in the development of renewable and sustainable structural bamboo products (SBPs). These SBPs are analogous to wood products such as plywood, oriented strand board and glue-laminated wood. In this study, the properties of natural Moso bamboo (Phyllostachys pubescens) are investigated to further enable the processing and design of SBPs. The radial and longitudinal density gradients in bamboo give rise to variations in the mechanical properties. Here, we measure the flexural properties of Moso bamboo in the axial direction, along with the compressive strengths in the axial and transverse directions. Based on the microstructural variations (observed with scanning electron microscopy) and extrapolated solid cell wall properties of bamboo, we develop models, which describe the experimental results well. Compared to common North American construction woods loaded along the axial direction, Moso bamboo is approximately as stiff and substantially stronger, in both flexure and compression but denser. This work contributes to critical knowledge surrounding the microstructure and mechanical properties of bamboo, which are vital to the engineering and design of sustainable SBPs.

Thermal conductivity of engineered bamboo composites

“…For example, in bamboo, cells and cell walls are not homogenous. Rather, vascular bundles (comprising of hollow vessels surrounded by sclerenchyma fibres with thick cell walls) are embedded in parenchyma cells with thin walls [25]. This heterogeneity in cell types and structure is not reflected in a single estimated characteristic value for the bamboo cell wall thermal conductivity.…”

“…The microstructure of wood and bamboo is fundamentally different ( Fig. 1): while both wood and bamboo have a cellular nature, cells in bamboo are principally axially oriented (as in a unidirectional composite) [25], while in wood some cells (viz. ray cells) are aligned in the radial/transverse direction.…”

“…Notably, applying the Halpin-Tsai equation to the experimental data also yielded similar values for the longitudinal thermal conductivity of the solid cell wall material. For the Halpin-Tsai equation, the geometric fitting factor n was based on an average longitudinal cell aspect ratio of 35-90, which in turn was calculated based on aspect ratios for sclerenchyma fibres (vascular bundles) and parenchyma cells of 100 [24] and 2 [25], respectively, and noting that sclerenchyma fibres form 35-90 % of the solid cell wall material [25]. The results of the Halpin-Tsai equation are not plotted on Fig.…”

Comparison of the structure and flexural properties of Moso, Guadua and Tre Gai bamboo

“…All of the Guadua and Tre Gai flexural tests were performed as part of this study. Some of the Moso flexural tests were previously reported by Dixon and Gibson (2014) while the remainder are from the literature (Li, 2004). The modulus of elasticity (MOE) was calculated from the slope of the middle 80% of the linear elastic portion of the load-deflection curve (r 2 > 0.99 for all fits) and the modulus of rupture (MOR) was calculated from the peak load.…”

“…Note the Moso relationships were obtained using the two combined data sets of Dixon and Gibson (2014) and Li (2004).…”