5. Conclusion

The principles of substructuring make it possible to explain the transformation of RITZ and modal recombination to arrive at the modal synthesis that integrates these two techniques. The rules for linking between substructures are explained.

Two methods have been developed in*Code_Aster*: the Craig-Bampton method and the MacNeal method. Here, we present their particularities, both in the definition of the initial modal base and in its exploitation.

After presenting the definition of a cyclic symmetric structure and the resulting properties, we presented the cyclic substructuring methods implemented in Code_Aster. They prove to be very interesting for calculating the natural modes of a cyclic symmetric structure, such as the rotors of rotating machines from which they take full advantage of their geometric and mechanical characteristics.