High-performance bamboo-wood composite materials based on the natural structure and original form of bamboo: Fracture behavior and mechanical characterization

Reducing the destruction of bamboo's original structure to produce high-utilization and high-performance engineered bamboo products has long been a goal in the industry. This study developed a new natural arcshaped laminated bamboo-wood lumber (NALBWL) based on the natural structure and original form of bamboo, using equal arc-shaped bamboo split (EASB) and poplar veneer. A multi-scale analysis of the bending performance and crack propagation dynamics of EASB and NALBWL was conducted. EASB's modulus of elasticity (MOE) and rupture (MOR) were 1.06 and 1.17 times higher than those of air-dried bamboo, respectively, exhibiting excellent mechanical properties. Additionally, its toughness in the full and elastic-plastic stages were 1.24 and 1.38 times higher than those of air-dried bamboo. NALBWL's MOE and MOR were 12.73 GPa and 174.41 MPa, fully meeting structural material requirements and even surpassing most engineered bamboo products. Moreover, NALBWL's radial bending load values were 2.29 and 2.24 times higher than that of EASB and air-dried bamboo, respectively, and it also demonstrated excellent water heat and drying resistance in impregnation and peeling performance. Real-time crack propagation analysis indicated that NALBWL's superior mechanical properties benefited from the respective advantages of bamboo and poplar veneer. This work showcased the application of "natural form-inspired design" in developing bamboo-wood composite materials, and the conclusion provided a reference for the sustainable development of engineered bamboo products and the study of biomass material fracture mechanisms.