In-situ investigation of deformation behaviors of moso bamboo cells pertaining to flexural ductility

Excellent flexural strength and ductility characteristics make bamboo an ideal natural material for many structural applications. This paper focuses on revealing the flexural ductility of moso bamboo (Phyllostachys edulis(Carr.) J. Houz.) at the cellular level. Scanning electron and three-dimensional X-ray microscopes were applied to examine the morphological changes and interaction of bamboo cells during the bending experiment. The flexural ductility of bamboo was investigated based on spatial arrangement and morphological structure of cells. During bending, bamboo cells were compressed in the longitudinal direction and elongated in the radial direction in the compressive layer. However, bamboo cells in the tensile layer were elongated in the longitudinal direction and shortened in the radial direction. Parenchyma cells had relatively larger deformation than other cells. The largest relative deformations of parenchyma cells reached - 4.49% (longitudinal direction) and 3.08% (radial direction) in the compressive layer and 2.33% (longitudinal direction) and - 0.47% (radial direction) in the tensile layer. Both parenchyma cells and vessels can function as a buffer against applied load and enhance the flexural ductility of bamboo. Fiber could restrict the deformation of its adjacent cells and provide strength for bamboo. Results revealed the mechanism of deforming of natural bamboo from the micro perspective and provided knowledge for bionic design on the basis of the morphological structure of bamboo.