Mode I fracture toughness properties of Plectocomia kerrana Becc (rattan) cane

Rattan is an important non-wood forest product, which shows a natural gradient in its structure from cane cortex to core. Toughness is its main characteristic, which is closely related to resistance to fracture. In this study, based on the principle of linear elastic fracture mechanics, the fracture toughness of Plectocomia kerrana Becc., was studied in two directions whose cracks were prefabricated from the cane cortex and from the cane core, respectively. The results showed that the average fracture toughness of pre-cracked from the rattan cane core was 0.476 MPa·m1/2 measured by the SENB method. This value is much smaller than bamboo, as well as fir, Masson pine and other woods. Nominal fracture toughness of pre-cracks from cane cortex measured by flexibility method was 0.263 MPa m1/2, which was less than the nominal fracture toughness value for pre-cracks from the core. When the rattan was bent, the crack in the rattan extended along with the prefabricated crack plane. Within the parenchymatic tissue, the crack extended transversely and changed its direction when the crack stretched into fiber sheath. The distribution density of vascular bundle was positively correlated with the fracture toughness.