Mechanical Characteristics of Bamboo Structure and Its Components

Abstract

In this chapter, first, the fine structure of bamboo is stated. Then the strength and elastic modulus of bamboo fiber and ground tissue are analyzed by mixture law and shear lag theory of meso-mechanics, and it is proved that bamboo fibers are the main component determining the mechanical characteristic of bamboo. Furthermore, results of tensile tests on separated bamboo fiber bundles show that the tensile strength of bamboo fiber obtained from the tests on bamboo blocks is higher than that on separated fiber bundles. This might be due to the interaction between components in bamboo in which parenchymatous ground tissue can pass loads and uniform the stresses loaded on fibers. And the differences of structure and strength between internodes part and node part of moso bamboo are studied. The results indicate that either in the non-epidermis-planning samples or in the epidermis-planning samples, the node does not take a declining effect on the bending strength, the longitudinal shearing strength, and the compressive strength. Instead, the node takes a reinforcing effect at different degrees. However, the node has a significant decline effect on the longitudinal tensile strength. By analysis on the structure of bamboo, it shows that though the vascular tissue passing bamboo node is curved and discontinuous at different degrees, bamboo is able to increase the bearing load area by expanding tissue at node, meanwhile, vascular bundles are thickened and entwined circuitously. So, the ability to anti-bending and anti-shearing of the culm under transverse load caused by snow or wind is increased by bamboo nodes. However, the tensile load born by the culm is less than other parts of culm during growth of bamboo. Therefore, the enlargement of node part and the structure evolution of nodes cannot enhance the tensile strength in the longitudinal direction.