A nonlinear anisotropic hyperelastic formulation for granular materials: comparison with existing models and validation

In this paper, the nonlinear anisotropic hyperelastic model recently proposed by Houlsby et al. (2019) is critically analysed and validated against experimental data. The model, here mainly discussed in terms of its strain energy function, is initially compared to existing formulations for the cases of nonlinear isotropic, linear anisotropic and the complete nonlinear anisotropic formulation. It is observed that the proposed model, which employs very few material parameters, encompasses most, but not all, of the existing anisotropic hyperelastic ones and provides a satisfactory fitting to laboratory experimental data observed on both sands and clays.