Applying VMOPT Method in Femap
Applying VMOPT Method in Femap
(OP)
Hello,
I am running a normal modes analysis for a model that incorporates the MFLUID virtual fluid mass, and I would like to use the VMOPT method described in the NX Nastran Advanced Dynamic Analysis User's Guide to decrease memory usage and solution time. I know that I need to specify the parameter VMOPT=2 to separate the computation of the dry and wet modes, but I can't figure out how to do that in Femap. Is it something I specify in the master requests and conditions, and if so can somebody help me understand how to do so?
Thanks for your help!
I am running a normal modes analysis for a model that incorporates the MFLUID virtual fluid mass, and I would like to use the VMOPT method described in the NX Nastran Advanced Dynamic Analysis User's Guide to decrease memory usage and solution time. I know that I need to specify the parameter VMOPT=2 to separate the computation of the dry and wet modes, but I can't figure out how to do that in Femap. Is it something I specify in the master requests and conditions, and if so can somebody help me understand how to do so?
Thanks for your help!





RE: Applying VMOPT Method in Femap
You need to play with PARAM,VMOPT in the NX NASTRAN BULK DATA:
For VMOPT = 0 or 2, mass is added in modal space to the reduced model. The global mass matrix is never augmented and this the grid point weight generator never "sees" the additional mass.
For VMOPT=1, mass is added to the global matrix. This makes the computation expensive for all but the smallest problems.
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Best regards,
Blas.
~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director
IBERISA
48004 BILBAO (SPAIN)
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