Set FORMULATION=MT (default) to use the Mori-Tanaka model as the homogenization
method.
Set FORMULATION=VOIGT to use the VOIGT model as the homogenization method.
Set FORMULATION=REUSS to use the REUSS model as the homogenization method.
Set FORMULATION=INVERSED MT to use the inversed Mori-Tanaka model as the homogenization
method.
Set FORMULATION=BALANCED to use the interpolative double inclusion model as the
homogenization method.