CDSMETH

Bulk Data Entry

CDSMETH - Run Control

Description

The CDSMETH command 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

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

Argument	Options		Description
CDSID	<INTEGER> Default = NONE		Identification number of CDSMETH.

GTYPE	<SVDNP, BME> Default = SVDNP	SVDNP:	Dynamic Stiffness Matrix is calculated by singular value decomposition of transfer function after scaling rotational DOF’s (Comment 5).
		BME:	Dynamic Stiffness Matrix is calculated by block matrix elimination (Comment 5).

TF	<YES, NO> Default = NO		Generate transfer functions at the connection and interior points at each loading frequency.

OSET	<INTEGER> Default = BLANK		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.

TOL	<REAL/BLANK> Default = 1.0e-20		Tolerance value for the Singular Value Decomposition (SVD) operation that involves pseudo–inversion of the transfer function matrix to obtain the dynamic stiffness matrix.

SSF	<REAL/BLANK> Default = 1.0		Structural scale factor used to scale transfer function terms associated with the structural degrees-of-freedom prior to the singular value decomposition (SVD) operation.

RSF	<REAL/BLANK> Default = 1.0e-3		Rotational scale factor used to scale transfer function terms associated with the rotational degrees-of- freedom prior to the singular value decomposition (SVD) operation.

CMSOUT	<CMSOUT/BLANK> Default = BLANK		This is an optional keyword to specify the creation of the component model synthesis (CMS) super element generated using the General Modal method with free – free boundary (Craig-Chang method).

SPID	<INTEGER>		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.

SPID_F	<INTEGER>		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.

GP_RC	<YES, NO> Default = NO		Grid participation recovery control. If 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.	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 FREQ# (# 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.

SDAMPING cannot be included in the generation of CMS superelements (CMSMETH entry). SDAMPING can be included in the generation of CDS superelements. If you used SDAMPING in the generation of the combined CDS and CMS (METHOD=GM) superelements, the SDAMPING will be included only in the CDS superelement. Use DMIGMOD to apply SDAMPING in the residual run to the CMS (METHOD=GM) superelements. If SDAMPING is not required for CMS superelements in the residual run, then the corresponding DMIGMOD data can be excluded from the model.