A hyperelastic isotropic model with Poisson’s ratio greater than one half

Abstract In this contribution, we propose a hyperelastic isotropic material model whose stress–strain response is non-linear even at infinitesimal deformations and cannot thus be linearized. As a result, the superposition principle does not apply and the generalized Hooke law is not valid even at small strains. A further unusual feature of this material model is that Poisson’s ratio can be greater than $$\varvec{0.5}$$ 0.5 in full agreement with the laws of thermodynamics. In particular, for the proposed strain energy function, a value of $$\varvec{\nu =0.644}$$ ν = 0.644 is reached. The model response appears to be plausible in various deformation states such as uniaxial tension/compression, simple shear, and pure dilation.