Analysis of tension and bending fracture behavior in moso bamboo (Phyllostachys pubescens) using synchrotron radiation micro-computed tomography (SRμCT)

Abstract

Abstract Bamboo is a natural bio-composite material that is both tough and possesses excellent mechanical properties. Its delicate structure and fiber arrangements play an important role in the mechanical properties and the fracture performance of bamboo. In this study, the fracture behaviors of bamboo due to tensile strength and bending were investigated using synchrotron radiation micro-computed tomography and environmental scanning electron microscopy (ESEM). Both tension and bending tests revealed that fibers are the key factors for bearing extra load and impeding crack propagation. Crack paths were found to be different in bamboo strips with different fiber percentages, and the interface between pulled-out fiber bundles and fiber break (in helix breaks and shearing break) was observed to be typical fracture characteristics in tension. Moreover, advanced micro-matrix cracking, interface debonding, fiber bundle bridging and the splitting of cell wall layers were found to be important fracture characteristics in bending. Both in tension and bending, a reasonably weak interface appeared to be beneficial for improving fracture toughness of fiber-reinforced bamboo. Thus, it is clear that “fiber bridging” mechanisms and “shear-lag theory” are well exhibited in bamboo.