Material symmetries of micropolar continua equivalent to lattices

Some aspects concerning the identification of continuum coarse models from fine discrete models are discussed. The preservation of the mechanical powe r, in the transition from the microscopic to the macroscopic description, i s required. A procedure based on the equivalence of the virtual power provi des a natural way to select the continuum satisfying this requirement. Havi ng the advantages of an integral procedure, it gives good results if the co arse model is a multifield continuum with strain fields compatible with tho se of the fine 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 defined and its transformation into that of an equivalent micropolar continuum is studied in detail. Numerical analyses are also performed to investigate the effect of change in the material symmetries. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.