Hi Sebastian, first of all, sorry for my late reply. Thank you very much for comment, it certainly raises some very interesting points. I think the only thing which is still left to be explained is the fact that a triangular grid, which yields the right isotropic result, becomes anisotropic just by rearranging the elastic properties to form squares-like clusters. I think this case does not correspond to any of your 4 points since I do this without h->inf. In fact, each of those clusters are just 2 FE.