A universal hyperelastic constitutive model with high stability and reliable prediction for elastomer nanocomposites

The use of elastomeric nanocomposite materials is pervasive in engineering fields, largely due to their large deformation characteristics. However, the customized material formulations and production processes result in highly complex stress-strain mechanical responses. It is of paramount importance to develop a hyperelastic constitutive model (HCM) that can enhance the reliability of efficient simulation design of rubber products. In order to address these challenges, a universal hyperelastic constitutive model called the Zhang-Li model with remarkable stability has been developed. The new model demonstrated the capacity to accurately capture the nonlinear mechanical characteristics of 57 uniaxial tensile (UT) stress-strain curves and three groups of UT, planar tensile (PT) and equibiaxial tensile (ET) stress-strain curves. A comparative study with four classical models (Neo-Hookean, Mooney-Rivlin, Yeoh, and Ogden models) demonstrates the significant advantages of the new model. The new model demonstrates the capability to reasonably predict PT and ET mechanical responses when only UT test data is provided, thereby ensuring Drucker stability across a wide strain range for the target materials. The model has been implemented in the finite element software Abaqus/Standard via the user-defined UHYPER subroutine interface, thus providing a powerful analytical tool for structural design and component optimization of rubber products.