Hello everyone, I have a question about anisotropic hyperelastic in abaqus.

Holzapfel material is Invariant-based formulation, when using hgo material, the keyword *ORIENTATION needs to be used to define the local coordinate system, which is used to define the direction of the fiber.

While the generalized Fung material is Strain-based formulation and has no fiber directions, is it necessary to define the local directions?

I found two input files "uaniso_inv_fung.inp" and "funganiso_mullins_ve.inp" in Abaqus Verification Guide->Material Verification->Mechanical properties->2.2.1Elastic materials->Anisotropic hyperelastic with generalized Fung strain energy function, which defines the local material directions.