I read that "In general, even if the materials on the micro-level are isotropic, the effective
material can show anisotropic behavior. A general anisotropic linear elastic material
may have twenty one independent material parameters.''
If I understand my results correctly then simple structures like ''ball in the unit cell'' result in orthotropic material.
I am a bit puzzled - what would be the simplest structure that would result in anisotropic material behaviour?