Theoretical and experimental research on anisotropic and nonlinear mechanics of periodic network materials

Abstract

Bio-inspired network materials composed of regularly aligned repeating filamentary microstructures exhibit promising application prospects in tissue engineering and bio-integrated devices due to the typical J-shaped mechanics curve precisely matched to the biological tissues. During the tensile process, an evident nonlinear mechanical anisotropy is induced by the drastic changes of microstructure geometries, which is of great concern in some particular requirements such as identifying the direction with the lowest or highest tensile stiffness and inducing alternate positive and negative or nearly zero Poisson's ratio. An efficient theoretical model for nonlinear anisotropic mechanics is developed in this paper by introduction of equilibrium and deformation compatibility conditions of presentative unit cell under finite uniaxial stretching along arbitrary directions, which is then verified by finite element analyses (FEA) and experiments both graphically and quantitatively. Through this model, the anisotropic mechanical responses of the periodic network materials are studied thoroughly and systematically based on the precise prediction of stress-strain relation, transverse-longitudinal strain relation and the deformed configuration. The effects of both the geometric parameters and the unit cell topology on the anisotropic mechanical responses are analyzed thereafter, which implies that the proposed model can play an instructive role in the design, optimization, and application of the periodic network materials.