Based on the volumetric-distortional decomposition of the deformation, a hyperelastic material is said to be fully decoupled if its strain energy potential is expressed as the sum of a term depending solely on the volumetric deformation and a term depending solely on the distortional deformation. This work aims at showing the consequences of the decoupling conditions in linear elasticity, in terms of the relationship with the linear elasticity tensor. The results show that, except for the case of isotropy, a material model based on a fully decoupled potential is in general not consistent with the linear theory, as some components of the linear elasticity tensor do not have a corresponding term in the non-linear potential. On the other hand, by applying the developed theory to the particular case of a decoupled potential, one obtains the conditions under which a purely hydrostatic stress causes a purely volumetric deformation. The latter conditions are also obtained in a straightforward way, by means of fourth-order tensor algebra.
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