Analysis and verification of a biomimetic design model based on fish skin

Abstract

Many biological architectures are Bouligand structures, which comprise uniaxial fiber layers stacked in a periodic helical arrangement and are characterized by high damage resistance. As an effective flexible protective structure, fish skin is a Bouligand structure that protects the body while ensure flexibility during swimming and predation. In this paper, an analytical model inspired by fish skin is established based on previous studies, and the parameters for describing crack growth are determined. Then, mathematical expressions for the local stress intensity factors and plastic zone are used to predict how the helical stacking angle α influences the crack propagation. The results show that crack deflection and twisting improve the fracture toughness of the composite structure greatly, with the optimal fracture toughness being that for α = 60° – 70°. Moreover, biomimetic flexible composite structures inspired by fish skin are produced using silicone and Kevlar fibers. Scanning electron microscopy is used to observe the cross-sectional morphology of the composite structures, showing that the interfaces between the silicone and Kevlar fibers are highly compact. Results from experimental impact tests agree well with the predicted results.

Fish scale inspired structures—a review of materials, manufacturing and models

“…It was observed that impact resistance decreases with increase in the helical stacking angle. SEM analysis was also done to find the relevant microstructure, showing the effective resistance of the biological structure against force in the composite (silicone and Kevlar fiber) [89]. Biomimetic armor was tested under dynamic impact using ElectroForce 3300 equipment (TA Instruments) and a ballistic test using a handgun.…”

“…In next step, Kevlar fibers were included in the solidified mold and covered with another part of the mixture, and the same curing process was repeated. Each sample had five layers of fibers and a constant helical angle [89].…”