CDSMETH

Bulk Data Entry Can be used in the component dynamic synthesis method for generating component dynamic matrices at each loading frequency.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CDSMETH CDSID GTYPE TF OSET TOL SSF RSF    
  CMSOUT SPID SPID_F GP_RC          

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
CDSMETH 10 SVDNP YES            
  CMSOUT 9000001 9000001 YES          

Definitions

Field Contents SI Unit Example
CDSID Identification number of CDSMETH.

Default = NONE (Integer)

  
GTYPE
SVDNP (Default)
Dynamic Stiffness Matrix is calculated by singular value decomposition of transfer function after scaling rotational DOFs. 5
BME
Dynamic Stiffness Matrix is calculated by block matrix elimination. 5
  
TF Generate transfer functions at the connection and interior points at each loading frequency.
NO (Default)
YES
  
OSET Grid set for interior grids. The responses corresponding to interior grids may be recovered in the residual run.

If OSET is specified, TF is automatically set to YES.

Default = BLANK (Integer)

  
TOL Tolerance value for the Singular Value Decomposition (SVD) operation that involves pseudo-inversion of the transfer function matrix to obtain the dynamic stiffness matrix.

<REAL/BLANK>

Default = 1.0e-20

  
SSF Structural scale factor used to scale transfer function terms associated with the structural degrees-of-freedom prior to the Singular Value Decomposition (SVD) operation.

<REAL/BLANK>

Default = 1.0

  
RSF Rotational scale factor used to scale transfer function terms associated with the rotational degrees-of-freedom prior to the Singular Value Decomposition (SVD) operation.

<REAL/BLANK>

Default = 1.0e-3

  
CMSOUT This is an optional keyword to specify the creation of the Component Model Synthesis (CMS) superelement generated using the General Modal method with free - free boundary (Craig-Chang method).

<CMSOUT/BLANK>

Default = BLANK

  
SPID The starting SPOINT ID to be used in CMS matrix output for the structural eigenmodes. There is no default. This is only valid, if CMSOUT is specified.

<INTEGER>

  
SPID_F The starting SPOINT ID to be used in CMS matrix output for the fluid eigenmodes. There is no default, if fluid grids are present in the model. However, this must be used, if there are fluid grids in the model. This is only valid, if CMSOUT is specified.

<INTEGER>

  
GP_RC Grid participation recovery control.
NO (Default)
YES
The fluid-structural interface connection matrix is calculated and stored as a part of the CMS super element. This is only valid, if CMSOUT is specified.
  

Comments

  1. CDSMETH is only supported for Modal Frequency Response Analysis subcase. The responses available for recovery, and the attachment points available for connection in the residual structure, must be specified on a BNDFRE1, BNDFREE, CSET or CSET1 data entry for a modal frequency response analysis in which CDSMETH has been specified.
  2. Frequencies available for recovery must be specified, using the FREQ or FREQ1 (# ranges from 1 to 5) data entries, in the modal frequency response analysis in which CDSMETH has been specified.
  3. A MODEL card may be used for additional response output for the optional CMS superelement output.
  4. Reasonable speedup may be achieved by reducing the number of CSET points in the residual run when CDSMETH is used.
  5. Performance may be an issue with the Block Matrix Elimination (BME) method for large models. The BME option is only recommended for small models or when other methods fail to work.
  6. SDAMPING cannot be included in the generation of CMS (CMSMETH entry). SDAMPING can be included in the generation of CDS . If you used SDAMPING in the generation of the combined CDS and CMS (METHOD=GM) , the SDAMPING will be included only in the CDS . Use DMIGMOD to apply SDAMPING in the residual run to the CMS (METHOD=GM) . If SDAMPING is not required for CMS in the residual run, then the corresponding DMIGMOD data can be excluded from the model.