Note that you can also compute orthotropic linear-elastic material properties if the constituent materials are nonlinear. The computed properties are then valid only in a small strain analysis.

If possible the nonlinear effects are ignored completely, similar to setting nonlinear material effects to Off in Mechanical (see Nonlinear Material Effects).

In case this is not possible (for instance, for hyperelastic materials) then the nonlinear material is used, which will lead to some errors in computing the linear elastic material behavior as the applied strain is not infinitesimal, but finite. However, the effect will be negligible in most cases.

Note that if large deformations are active, input material properties based on strain-stress curves are interpreted as true strain vs. true stress, as discussed in Define Part Behavior in the Mechanical User's Guide.

The material properties are corrected for the fact that true strain rather than engineering strain is the active strain measure. Similarly, the area changes are taken into account when computing material properties.

However, it is not possible to setup a "clean" shear case if large deformations are active; there are always some other macroscopic strains that are non-zero (see the figure Polar Decomposition of a Shearing Deformation, under Large Deformations in the Mechanical APDL Theory Reference and the corresponding description). Once again, the effects will be negligible in most cases given that the applied shear is small.