5. Summary of results

The results obtained are excellent since the frequency differences with the reference solution are less than \(\text{0.03\%}\). In addition, Code_Aster well detects the 6 rigid body modes, which we did not ask to calculate.

To effectively calculate rigid modes, two possibilities exist. With the “BANDE” option on the \((\mathrm{0,}3000\mathrm{Hz})\) frequency band, you can use either the “SORENSEN” method or the LANCZOS (“TRI_DIAG”) method by specifying the “MODE_RIGIDE” option.