PARAM CARDS IN NASTRAN 1

[montyk]

HI EVERYONE,

I'VE BEEN USING MSC.NASTRAN SOFTWARE RECENTLY AND HAVE USED FEW PARAM CARDS LIKE K6ROT, AUTOSPC. CAN ANY ONE PLEASE EXPLAIN ME THE PURPOSE OF THESE CARDS AND ALSO WHAT ARE OTHER PARAM CARDS USED IN STRUCTURAL ANALYSIS AND THE PURPOSE OF THEIR USE

REGARDS,

 

[BlasMolero]

Hello!,
• K6ROT specifies the stiffness to be added to the normal rotation for CQUAD4 and CTRIA3 elements. This is an alternate method to suppress the grid point singularities, and is intended primarily for geometric nonlinear analysis. A value between 1.0 and 100.0 is recommended to suppress singularities. A large value may be required in nonlinear and eigenvalue analyses. This parameter is ignored for CQUADR, CTRIAR, CQUAD8, and CTRIA6 elements. K6ROT is forced to 0 when only membrane elements exist.

• AUTOSPC specifies the action to take when singularities exist in the stiffness matrix [Kgg]. AUTOSPC=YES means that singularities will be constrained automatically. AUTOSPC=NO means that singularities will not be constrained. If AUTOSPC=NO is set, then the user should take extra caution analyzing the results of the grid point singularity table and epsilon.

See “Constraint and Mechanism Problem Identification in SubDMAP SEKR” in the NX Nastran User’s Guide for details of singularity identification and constraint. Singularity ratios smaller than PARAM,EPPRT (default = 1.E-8) are listed as potentially singular. If PARAM,AUTOSPC has the value YES, identified singularities with a ratio smaller than PARAM,EPZERO (default = 1.E-8) will be automatically constrained with single-point constraints. If PARAM,EPPRT has the same value as PARAM,EPZERO (the default case), all singularities are listed. If PARAM,EPPRT is larger than PARAM,EPZERO, the printout of singularity ratios equal to exactly zero is suppressed. If PARAM,PRGPST is set to NO (default is YES), the printout of singularities is suppressed, except when singularities are not going to be removed. If PARAM,SPCGEN is set to 1 (default = 0), the automatically generated SPCs are placed in SPCi Bulk Data entry format on the PUNCH file.

AUTOSPC provides the correct action for Superelements in all contexts. It is ignored for the residual structure in SOLs 106, 129, 153 and 159 when the solution is either material nonlinear or geometric nonlinear. PARAM, AUTOSPCR, not AUTOSPC, is used for the o-set (omitted set) in the residual structure in SOLs 106 and 153.


Etc.. everything is on the manuals, take a look to the QRG (QUICK REFERENCE GUIDE), all is there!!.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

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