Issue on page /chapter2/hyperelasticity.html

[127rifat]

It would helpful to include the functional form and weak form derivation for the hyperelastic beam problem example.

[jorgensd]

I would probably refer to: http://jsdokken.com/FEniCS23-tutorial/src/ufl_formulation.html#functionals-and-derivatives
which goes through the functional version of linear elasticity.

[127rifat]

I was actually referring to the nonlinear hyperelasticity problem for deformation of a beam

[jorgensd]

I get that you want that included in this demo.
However, the functional principle is the same for both linear and the non-linear problem:

1. Formulate an energy functional
2. Take it's first and second variation.