XDAMP

Bulk Data Entry Defines the values for Raleigh damping for geometric nonlinear dynamic analysis.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
XDAMP DID GSID ALFA BETA          

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
XDAMP 100 34 3.0 1.0          

Definitions

Field Contents SI Unit Example
DID Unique damping identification number.

(Integer ˃ 0)

  
GSID Grid set identification number. Damping is applied to the grid points in this set.

Default = all grids in the model (blank or Integer ˃ 0)

  
ALFA Factor for the stiffness matrix contribution.

(Real ˃ 0)

  
BETA Factor for the mass matrix contribution.

(Real ˃ 0)

  

Comments

  1. Rayleigh damping is applied to all geometric nonlinear dynamic analysis subcases, implicit and explicit. It is ignored in all other subcases.
  2. In implicit dynamic analysis damping is applied to all grid points and GSID is ignored. Multiple XDAMP is not allowed in implicit dynamic analysis.
  3. XDAMP and PARAM W3/G are mutually exclusive.
  4. Grid sets in all XDAMP statements must contain unique sets of grid points.
  5. The viscous damping matrix B is calculated from the mass matrix M and stiffness matrix K using:(1)
    B = A L F A ⋅ M + B E T A ⋅ K MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY=Hhbbf9v8 qqaqFr0xc9pk0xbba9q8WqFfea0=yr0RYxir=Jbba9q8aq0=yq=He9 q8qqQ8frFve9Fve9Ff0dmeaacaGacmGadaWaaiqacaabaiaafaaake aacaWGcbGaeyypa0JaamyqaiaadYeacaWGgbGaamyqaiabgwSixlaa d2eacqGHRaWkcaWGcbGaamyraiaadsfacaWGbbGaeyyXICTaam4saa aa@4814@
  6. This card is represented as an interface in HyperMesh.