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This command makes it possible to calculate the real or complex natural modes, as well as the harmonic response (displacement, speed, acceleration) of a structure comprising viscoelastic materials whose properties depend on the frequency (which results in a stiffness matrix dependent on the frequency).

The following actions are possible:

• obtaining modes by iterative method; 3 types of modes to choose from: real modes, real beta-modes or complex modes, taking into account the frequency dependence of the mechanical properties of viscoelastic materials;

• if there is an excitation, calculation of the harmonic response of the structure; the calculation is done by projection on the modal base established in the previous step, then reproduction on the physical base.

For more theoretical details, refer to the reference document [R5.05.10].

The command can produce a concept such as mode_meca, mode_meca_c, dyna_harmo.

**Note:*

The command does not currently allow the calculation of dual modes;

The calculation of structures with rigid body modes may not converge.