Material symmetries of micropolar continua equivalent to lattices

Some aspects concerning the identi_cation of continuum coarse models from _ne discrete models are discussed[ The preservation of the mechanical power\ in the transition from the microscopic to the macro! scopic description\ is required[ A procedure based on the equivalence of the virtual power provides a natural way to select the continuum satisfying this requirement[ Having the advantages of an integral procedure\ it gives good results if the coarse model is a multi_eld continuum with strain _elds compatible with those of the _ne model[ In this situation both models share the same material symmetry group[ This is shown with reference to rigid particle systems[ In particular\ the symmetry group of the discrete material is de_ned and its transformation into that of an equivalent micropolar continuum is studied in detail[ Numerical analyses are also performed to investigate the e}ect of change in the material symmetries