Real-time flexural fracture behaviors and toughening mechanisms of bamboo slivers with different fiber content and moisture content

Bamboo has great potential for manufacturing heterotypic engineered components, owing to its excellent flexibility and toughness. To better understand how bamboo sliver fractures behave after bending and to learn what biophysical properties of bamboo contribute to their flexural toughness, bamboo slivers with different fiber cell (FC) contents and moisture contents (MCs) were placed under buckling load and real-time cracking behaviors were observed using in situ microscopy and analyzed by Python. The results showed that the presence of more FC or MC in bamboo led to a later generation and slower propagation of cracks during the bending process. The tensile strength of the pure FC was significantly greater than that of the pure parenchyma cell (PC), causing cracks to deflect when they reached the FC. Both FC’s and PC’s tensile properties decreased as MC increased, indicating that water weakens the links in bamboo and results in more fracture deflections. Therefore, both fiber and moisture contributed to toughening by deflecting fractures. This study provides critical experimental evidence on the effects of the fibrous structure and water content on the flexural fracture behaviors of bamboo slivers. Furthermore, it provides a theoretical foundation for the selection of raw materials for bamboo-winding and bamboo-woven composites.