Stepwise Failure Behavior of Thermal-Treated Bamboo Under Uniaxial Tensile Load

Abstract

In this paper, the tensile behavior of Moso bamboo (Phyllostachys pubescens) before and after heat treatment was studied. The tensile strength and the stress-strain curve of the specimens were acquired. Then the crack propagation process during tension was analyzed. The microstructure and chemical composition analysis was conducted to discover the mechanism underneath the mechanical behavior. The tensile strength decreases with the increasing treating temperature. The chemical analysis indicated that the decrease in tensile strength resulted from the decomposition of cellulose and hemicellulose. The unique composite structure of bamboo makes it shows stepwise failure behavior under uniaxial tensile load. During tension, the fiber sheaths disperse in the ground parenchymatous tissue, and break dispersively during tension, making the strain-stress curve fluctuate like stairs. The curve of the specimen got more fluctuant with the increase in treating temperature. The microstructure analysis indicates that the structural change of the fiber cell wall is responsible for the more fluctuant strain-stress curve.

Keywords: Moso bamboo, Thermal treatment, crack propagation, longitudinal tensile fracture, fracture mechanism