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*MODAL DAMPING

Keyword type: step

This card is used within a step in which the *MODAL DYNAMIC or *STEADY STATE DYNAMICS procedure has been selected. It allows for Rayleigh damping in a global way, i.e. the damping matrix is taken to be a linear combination of the stiffness matrix and the mass matrix :

| (121)

The coefficients apply to all modes. The corresponding friction coefficient for mode j amounts to:

| (122)

Consequently, damps the low frequencies, damps the high frequencies.

The only parameter RAYLEIGH is required.

First line:

- *MODAL DAMPING,RAYLEIGH

Second line:

- not used (kept for compatibility reasons with ABAQUS)
- not used (kept for compatibility reasons with ABAQUS)
- Coefficient of the mass matrix .
- Coefficient of the stiffness matrix .

    Example:

    *MODAL DAMPING,RAYLEIGH
    ,,0.,2.e-4

indicates that the damping matrix is obtained by multiplying the stiffness matrix with

Example files: beamdy3, beamdy4, beamdy5, beamdy6.

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