Study on the correlation between the puncture impact performance of arc-shaped bamboo splits and bamboo ages

The unique hierarchical gradient structure of bamboo from the macro to nano scales and its remarkable com-bination of vascular bundles and parenchyma provide its high strength and toughness. Bamboo is an excellent engineering material that is widely used in construction and transportation, and its impact performance is an important indicator that reflects its structural stability. In this study, the finite element method was used to analyze the mechanical characteristics of bamboo splits under impact in simulations, and arc-shaped bamboo splits were tested to assess impact performance under puncture, thus, clarifying the relationship between bamboo age, density, and chemical composition and fracture load. As the bamboo age increased (from 2 to 4 and 8 years), the maximum impact load of bamboo first increased and then decreased. The maximum impact load of 4-year-old bamboo was 4373 N, which was 1.79-and 1.70-fold that of 2-and 8-year-old bamboo, respectively. Although the maximum impact load of 2-year-old bamboo was lower than that of 4-year-old bamboo, it nevertheless withstood secondary loads after fracture and was highly tough. Specimens exhibited both transverse and intergranular impact fractures, but the latter category comprised most of the fractures. The crack deflection, fiber stripping, and crack bridging caused by the gradient structure of bamboo enhanced its fracture load. There were clear correlations between the maximum load of bamboo impact and the density, moisture content, and chemical composition of bamboo. The establishment of structure-activity relationships between the bamboo impact load and physicochemical properties can guide the engineering applications of bamboo and provide a reference for biomimetic materials.