Novel Constitutive Modeling Approach for Dry Fabrics and Fabric-Reinforced Elastomers

Fabric-reinforced elastomers are widely used in many industrial areas such as the fabric-reinforced rubbers and fabrics with a partially cured polymer matrix. The fabric-reinforced elastomers usually consist of fabric reinforcements combined with a soft elastomer. In such a material system, the deformation response is primarily controlled by the fabric, and the elastomer sever as a binding material to provide structural support. The fabric reinforcement in the composites provides high in-plane stiffness due to the high Young’s modulus of the fiber. Advances in textile technologies, including stitching, weaving, braiding, and knitting, allow for various fabric architectures to be used as reinforcements, resulting in anisotropic constitutive behavior of the composite. Compared with traditional fiber-reinforced polymer matrix composites that have a much higher stiffness, fabric-reinforced elastomers offer better deformability due to the low bending stiffness. To fully achieve the advantage of designing with composites, it is important to develop a robust, physics-based model to understand how the matrix and reinforcement properties affect the deformation response of the composite. The focus of this study is to develop a constitutive modeling approach for the dry fabrics and fabric-reinforced elastomers. The strain energy-based framework is used to formulate the effective strain energy density function for a representative unit cell of these material systems. The fabric reinforced elastomer is studied to understand the effect of the reinforcement architecture and the constituent properties. In this study, the proposed material constitutive model is also applied to predict the deformation response of dry fabrics during the fabric draping process. The material properties used in the proposed model are based on the constituent material properties that can be characterized experimentally. The validation of the proposed material model for the fabric-reinforced elastomer is performed through a full 3D Finite Element (FE) model in which the elastomer and fabric are explicitly modeled. Another application of the strain energy-based framework on the dry fabric is validated by predicting the angle change between the fibers during the hemisphere draping experiment. The implementation of the proposed material model is addressed by formulating the stress update strategy and consistent Jacobian matrix in the commercial FE software Abaqus.