Modeling of anisotropic hyperelastic heterogeneous knitted fabric reinforced composites

Knitted fabrics are used to manufacture soft implants for medical applications. Once integrated in the body, the fabric forms a new composite material with the native and scar tissues. The mechanical behavior of the composite is assumed to be hyperelastic to match with the physiological behavior of the native tissues and thus to improve the fabric in vivo integration. Being able to predict the mechanical behavior of the composite regarding the tissue nature and the textile properties would accelerate the choice of the appropriate knit. We propose an approach for modeling the mechanical behavior of an hyperelastic material reinforced by a knitted fabric. The main idea of the modeling approach described in the present paper is to couple micro or meso-structural observations with mechanical considerations. Knitted fabric composites display oriented and periodic microstructures. Since most knitted fabrics present a non-linear anisotropic mechanical behavior, the hyperelastic directional formalism seems appropriate to model the reinforced elastomer. This work focuses on the development of a new directional model for the mechanical representation of anisotropic knitted fabric reinforced elastomers. The material is described with the help of a discrete network of directions that contribute distinctively to the material’s global behavior. Experimental data obtained on reinforced elastomer composites were used to confirm the accuracy of the results as well as the prediction capabilities of the model. It seems able to represent an anisotropic stress answer of microstructured composite in uniaxial tension.