Quasi-brittle fracture criterion of bamboo-based fiber composites in transverse direction based on boundary effect model

摘要

Bamboo and engineered bamboo products have gathered increasing scientific and technological interests for its promising applications in sustainable engineering purpose. Bamboo-based fiber composites, a main example of engineered bamboo products, is fabricated from processing the raw bamboo bundles treated with water-soluble resin into a bamboo fiber reinforced bio-composite. The present work investigates the transverse mode-I fracture criterion of bamboo-based fiber composites: the tensile strength f(t) and fracture toughness K-IC. The fiber bundles are taken as the "aggregates" of this material, and the average grain size G is determined as 0.4 mm. By the experimental curve between the applied load and the mid-span deflection from the three-point-bending test on single edge notched specimens, the fracture process as well as the crack development includes three stages: linear, softening and failure stages. The quasi-brittle fracture criterion is calculated with the experimental peak load P-max according to the boundary effect model in non-linear elastic fracture mechanics. Also, the normal distribution analysis is applied to cover all the experimental scatters with desired reliability. Furthermore, the method in this work on bamboo-based fiber composites can be extended to study other fiber reinforced composites.