diff --git a/docs/examples/example_neohooke.md b/docs/examples/example_neohooke.md index 634edad..ed06fa6 100644 --- a/docs/examples/example_neohooke.md +++ b/docs/examples/example_neohooke.md @@ -9,14 +9,12 @@ parent: Examples This is a very basic example on how to implement a nearly-incompressible version of the Neo-Hookean material model in a commercial FEM package (HYPELA2 for Marc). As no special two- or three-field variational principle is used in this example, it is not suitable for nearly-incompressible material behaviour. Otherwise the elements tend to show excessive volumetric locking during deformation and hence, wrong results are calculated. -The strain energy density function per unit reference volume is additively splitted into an isochoric and volumetric contribution, see $$\eqref{eq:psi}$$. The first one is assumed to be proportional to the first invariant of the isochoric part of the right Cauchy-Green deformation tensor whereas the volumetric part is only a function of the volumetric ratio (the determinant of the deformation gradient). +The strain energy density function per unit reference volume is additively splitted into an isochoric and volumetric contribution, see \eqref{eq:psi}. The first one is assumed to be proportional to the first invariant of the isochoric part of the right Cauchy-Green deformation tensor whereas the volumetric part is only a function of the volumetric ratio (the determinant of the deformation gradient). -$$ \begin{equation} \psi(\mathbf{C}) = \psi(\mathbf{\hat C}) + U(J) \label{eq:psi} \end{equation} -$$