A Constitutive Model of Hyperelastic Anisotropic Materials: Approach and Implementation in ABAQUS

ABAQUS provides the-state-of-the-art capabilities in hyperelastic modeling of rubber and other isotropic elastomers. Practical interest, however, is often focused on anisotropic elastomer-like materials (e.g., bio-tissues, cord-rubber composites, reinforced polymers, etc.) where properties in various directions are significantly different. The present paper considers a general constitutive model of hyperelastic anisotropic behavior and its implementation in ABAQUS. Major idea of the model is to consider two finite elements to model the same physical volume, where one element controls incompressibility, while the other one is anisotropic. Thus, the proposed model is capable to account for both incompressible (or almost incompressible) behavior as well as the most general type of 3-D anisotropic deformation. The phenomenological nature of the model is based on assumption that necessary experimental data (e.g., stress-stretch curves in different directions) are available for different loading cases. Detailed implementation of the model in ABAQUS is proposed, and simplicity of the implementation is emphasized. It is noted that it does not require additional programming and may be practically performed using existing options of ABAQUS. The robust nature of the model is computationally illustrated on a representative example. Advantages of the proposed model in contrast with FEA models with rebars (conventional approach) are discussed.