Multiscale understanding in fracture resistance of bamboo skin

Abstract Bamboo has been widely used in construction for its high strength, lightweight and low cost. It usually fails from the skin because of macroscopic fiber splitting. Previous research focused on the strength of bamboo at structural scale without insight to its chemistry and microstructure of the skin and how they relate to its facture. In this research, we combine multiscale computational modeling with experimental methods to characterize the distribution of silica particles within the bamboo skin and investigate their effect on fracture. We use microscope to characterize the chemical and microscopic feature of bamboo skin and find silica particles generally distributed in bamboo skin and their pairwise distances follow a normal distribution. We use molecular dynamics simulations and finite element analysis to investigate the effect of silica particles and their unique distribution on the fracture of bamboo skin. It is noted that the silica forms a perfect bonding interface to cellulose fibers and the particles significantly increase the critical stress up to 6.28% than pure cellulose matrix for cracks that randomly occurs. We find that such an enhancement in critical stress against random cracks is only guaranteed by the distribution of silica particles in bamboo skin, as such an enhancement is not observed for other randomly assigned silica particles, suggesting that the silica distribution in bamboo skin is optimal for critical stress improvement for random cracks. This research output can inspire the development of more durable and sustainable bamboo products as well as innovative synthetic composite materials.