title: Hole-pin joining structure with fiber-round-hole distribution of lobster cuticle and biomimetic study.
abstract: Observations of the cuticle of the Boston Spiny Lobster using scanning electron microscope (SEM) show that it is a natural biocomposite consisting of chitin fibers and sclerotic-protein matrix with hierarchical and helicoidal structure. The SEM images also indicate that there is a hole-pin joining structure in the cuticle. In this joining structure, the chitin fibers in the neighborhood of the joining holes continuously round the holes to form a fiber-round-hole distribution. The maximum pullout force of the fibers in the fiber-round-hole distribution, which is closely related to the fracture toughness of the cuticle, is investigated and compared with that of the fibers in non-fiber-round-hole distribution based on their representative models. It is revealed that the maximum pullout force of the fibers in the fiber-round-hole distribution is significantly larger than that of the fibers in the non-fiber-round-hole distribution, and that a larger diameter of the hole results in a larger difference in the maximum pullout forces of the fibers between the two kinds of the fiber distributions. Inspired by the fiber-round-hole distribution found in the cuticle, composite specimens with the fiber-round-hole distribution were fabricated with a special mold and process to mirror the fiber-round-hole distribution. The fracture toughness of the biomimetic composite specimens is tested and compared with that of the conventional composite specimens with the non-fiber-round-hole distribution. It is demonstrated that the fracture toughness of the biomimetic composite specimens with the fiber-round-hole distribution is significantly larger than that of the conventional composite specimens with the non-fiber-round-hole distribution.
authors.affiliation: College of Aerospace Engineering, Chongqing University, Chongqing 400044, China; Chongqing Key Laboratory of Heterogeneous Material Mechanics, Chongqing University, Chongqing 400044, China. Electronic address: bchen@cqu.edu.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.affiliation: Division of Mechanical Engineering, Alfred University, Alfred, NY 14802, USA.
authors.forename: Jinghong
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA.
authors.forename: Jihua
authors.initials: J
authors.lastname: Gou
authors.affiliation: College of Aerospace Engineering, Chongqing University, Chongqing 400044, China.
authors.forename: Shiyun
authors.initials: S
authors.lastname: Lin
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D032701:Biomimetics; D002686:Chitin / Q000378:metabolism; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D033521:Palinuridae / Q000033:anatomy & histology* / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D002686:Chitin
keywords: Biomimetic fabrication; Boston spiny lobster cuticle; Fiber-round-hole distribution; Hole-pin joining structure; Maximum pullout force