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The material type for a Neo-Hookean material is neo-Hookean. The following parameters must be defined:
|<v>||Poisson's ratio||[ ]|
This model describes an unconstrained Neo-Hookean material . It has a non-linear stress-strain behavior, but reduces to the classical linear elasticity model for small strains and small rotations. It is derived from the following hyperelastic strain-energy function: Here, and are the first and second invariants of the right Cauchy-Green deformation tensor and is the determinant of the deformation gradient tensor. The relationship between the material parameters, E, and v, and the parameters used in the strain-energy function, is as follows.
This material model uses a standard displacement-based element formulation, so care must be taken when modeling materials with nearly-incompressible material behavior to avoid element locking. For this case, use the Mooney-Rivlin material described in Section 184.108.40.206↑.
<material id="1" type="neo-Hookean"> <E>1000.0</E> <v>0.45</v> </material>