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Differential Stiffening Run with DMIG entries

N/A

After running some test cases, it looks pretty clear that if your model includes
DMIG entries for hardware, that hardware is not included in either the Grid Point
weight generator summary OR the modal solution when attempting a differential stiffening
(STATSUB routine) solution. Run a simple cantilevered beam model, then replace
the second half of it with a DMIG representation of the mass and stiffness. Each
model will give the exact same answers for a normal modes solution. But now if
you apply a distributed load to only the first physical element and set that load
to 0.0 lb/in you should once again get exactly the same results. For the model
with only CBEAM elements you will. However, for the model where half is a DMIG,
you will get the exact results for only a cantilver beam of the half-length (the
length still represented by CBEAMs). Somewhere in the STATSUB routine NX is losing
the DMIG entries.
Anyone else seen this?
1 REPLY

Re: Differential Stiffening Run with DMIG entries

N/A

I'll answer my own post with the obvious correction; the K2GG, M2GG Case Control
cards are location dependent in the Case Control. Relocating the cards prior to
the first subcase corrects the problem. Glad I had someone more in tune with the
obvious to point that out...
"Tony Williams" wrote:
>
>After running some test cases, it looks pretty clear that if your model includes
>DMIG entries for hardware, that hardware is not included in either the Grid
>Point
>weight generator summary OR the modal solution when attempting a differential
>stiffening
>(STATSUB routine) solution. Run a simple cantilevered beam model, then replace
>the second half of it with a DMIG representation of the mass and stiffness.
> Each
>model will give the exact same answers for a normal modes solution. But now
>if
>you apply a distributed load to only the first physical element and set that
>load
>to 0.0 lb/in you should once again get exactly the same results. For the
>model
>with only CBEAM elements you will. However, for the model where half is a
>DMIG,
>you will get the exact results for only a cantilver beam of the half-length
>(the
>length still represented by CBEAMs). Somewhere in the STATSUB routine NX
>is losing
>the DMIG entries.
>
>Anyone else seen this?