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NASTRAN OLOADs & SPCFORCE RESULTANTs for thermal loads and SPCDs

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bhikku

Aerospace
Nov 12, 2009
1
All,

I've got a general enquiry to help my understanding of something. I've recently been checking through a thermal run that I've conducted (large & relatively complex model but simple thermal load applied globally across the FEM and relatively simple contraints) and have found that both the OLOAD and SPCFORCE RESULTANTs are non-zero and different. Under "normal" loads the model behaves as expected with OLOADs & SPCFORCEs in equilibrium. Can anyone explain why this might be the case as the literature on this topic is pretty brief.

I've got a similar problem with a run for the same model where I've loaded the FEM using enforced displacements. In this instance the OLOADs are zero as expected but the SPCFORCEs aren't.

In both instances the resulting loads are small but don't appear to be residual.

Help from anyone who's seen similar things would be appreciated!
 
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If your applying a thermal case, then due to expansion/contraction your SPCs will have to pick up load for equilibrium.
 
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