title: Hierarchical, multilayered cell walls reinforced by recycled silk cocoons enhance the structural integrity of honeybee combs.
abstract: We reveal the sophisticated and hierarchical structure of honeybee combs and measure the elastic properties of fresh and old natural honeycombs at different scales by optical microscope, environmental scanning electron microscope, nano/microindentation, and by tension and shear tests. We demonstrate that the comb walls are continuously strengthened and stiffened without becoming fragile by the addition of thin wax layers reinforced by recycled silk cocoons reminiscent of modern fiber-reinforced composite laminates. This is done to increase its margin of safety against collapse due to a temperature increase. Artificial engineering honeycombs mimic only the macroscopic geometry of natural honeycombs, but have yet to achieve the microstructural sophistication of their natural counterparts. The natural honeycombs serve as a prototype of truly biomimetic cellular materials with hitherto unattainable improvement in stiffness, strength, toughness, and thermal stability.
authors.affiliation: State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871, China. KarihalooB@cardiff.ac.uk
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Huiling
authors.initials: H
authors.lastname: Duan
authors.forename: Bhushan L
authors.initials: BL
authors.lastname: Karihaloo
authors.forename: Jianxiang
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D001516:Bees / Q000033:anatomy & histology* / Q000737:chemistry; D012831:Bombyx / Q000033:anatomy & histology*; D002473:Cell Wall / Q000648:ultrastructure*; D004548:Elasticity; D008855:Microscopy, Electron, Scanning; D047011:Silk; D013718:Tensile Strength; D014885:Waxes / Q000032:analysis
chemical_list: D047011:Silk; D014885:Waxes; C038228:beeswax