[Getfem-users] material law with non-symmetric stiffness

[Andriy Andreykiv]

Dear Getfem users,

I would like to use a non-linear elasticity brick with my own material
law that has non-symmetric stiffness matrix.
It's non-symmetric if you write it with Voigt notations, but of
course, two other "standard" symmetries of a full C_{ijkl} tensor are
present (i-j symmetry and k-l symmetry).
When I looked into getfem_nonlinear_elasticity.h I  found a comment
(next to virtual void grad_sigma declaration):

"// the result of grad_sigma has to be completely symmetric."

Does this comment imply the above mentioned two symmetries or it means
that a non-symmetry that also reveals itself
in material matrix, written in  Voigt notations, is also not allowed?
A simple example would be: Can I use a fully orthotropic material in
non-linear elasticity brick?
I browsed through the code of "getfem::nonlinear_elem_term " but it
doesn't look like any symmetry is required.
However, I would like to be sure.

Thank you in advance,
                                     Andriy