A textile architecture-based hyperelastic model for rubbers reinforced by knitted fabrics

Abstract

A new anisotropic hyperelastic model has been developed to model the deformation response of a knitted-fabric-reinforced rubber composite. The composite has a sandwich structure with a fiber net layer embedded in two rubber layers. Due to the architecture of the knitted fabric, the composite demonstrates an anisotropic hyperelastic response, which is modeled through a strain energy density function that incorporates the effects of deformed rubbers and stretched fibers. The rubber is considered as a neo-Hookean material, while the knitted fabrics are modeled as cords with negligible stiffness in bending. The effect of reinforcement comes from the conservation of the total length of the fiber cords. In addition, a slack variable is proposed to account for the effect of processing-induced fabric pre-stretch or fabric slack on the resulting composite response. This novel approach enables the determination of the constitutive behavior of the composite in closed form based on the constituent rubber and fiber properties and fabric architectures. The proposed analytical model is validated through a full 3D finite element (FE) model, in which the rubber and fiber reinforcement are modeled explicitly. Since the proposed model captures the key parameters that dictate the deformation response of knitted-fabric-reinforced composites, it can be employed as an efficient modeling tool to guide the design of rubbers and fabric architectures with targeted composite performance.