Simulating Chains in NX
Simulating Chains in NX
(OP)
I know this is a very vague question, but what 1D element/connection would be best suited for modeling tie-down chains? Obviously chains can not take compression but tension only. Any suggestions?
Thanks
Thanks





RE: Simulating Chains in NX
RE: Simulating Chains in NX
The element CROD of NX NASTRAN may have material nonlinear extensional properties, with linear torsion. You may supply plastic or nonlinear elastic material properties. Since the stress-strain curve for compression need not be the same as for tension, this element can, for example, be used to model cables which cannot carry compression. Of course, the analysis should be nonlinear (SOL106).
Best regards,
Blas.
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Blas Molero Hidalgo
Ingeniero Industrial
Director
IBERISA
48004 BILBAO (SPAIN)
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Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/
RE: Simulating Chains in NX
Thanks.
RE: Simulating Chains in NX
PS I'd probably go with the chain links in contact at the start and use displacement control, rather than load control, to avoid contact stabilization matters.
PPS Obviously I'm assuming you have a solver capable of running this sort of model.
RE: Simulating Chains in NX
Thanks.
RE: Simulating Chains in NX
i think you need to say the cable becomes slack when x% of the loadcase is applied, and 1-x% is rected by the remaining three cables. maybe easier to see by superposition ...
1) initially all cables have tension, Ti,
2) apply x% of the load, reacted by four cables, get cable loads (one should be -Ti),
3) apply 1-x% of the load reacted by the other three cables,
4) sum the cable loads (one will be zero).
you can calculate x by applying 100% load seeing the compression load in the cable, C, then x = Ti/(Ti-C) ... C being -ve.
instead of a myriad of cases, can you examine the corners of the envelop, 8 cases ? how much precision do you need ?
another day in paradise, or is paradise one day closer ?
RE: Simulating Chains in NX
some codes have "cable" elements that'd work as you want them to (tension only).
another day in paradise, or is paradise one day closer ?
RE: Simulating Chains in NX
RE: Simulating Chains in NX
how about the envelop idea (instead of considering every combination); that would give you fewer combinations, no?
another idea would be a unit load approach?
and once you eliminate a cable, the remaining three are statically determinate ? well, maybe ... how do you account for the deck reaction ? a vertical load under each (effective) corner ?
another day in paradise, or is paradise one day closer ?