Why Point Mass not Simple Modeling of Subsystems in Assembly

[sarclee]

During modeling assembly, always assume subsystems as point mass with MOI if the subsystem is large...

But why don't we model the subsystem in a simplified model (shell models)?

When we want to check for coupling issue, we then better to use reduced model for subsystems to be integrated with spacecraft?

 

[SWComposites]

what is stopping you from detail modelling the subsystem?
and I'm not sure what your question really is.

 

[IRstuff]

You can do whatever you want; no one is stopping you.

The question is whether you have time/resources to create a "simplified model" that only exists for your analysis and whether it really matters to the analysis. That's where your experience comes in; if the "simplified model" is only improving accuracy by 5% or 10%, was it worth the extra effort? Note that I don't know what the actual improvement is, but there will be some improvement, and you need to judge that on a case-by-case basis.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[GregLocock]

It used to come down to run time and wavefront (number of equations being solved at any one time) limitations, so that's why FEA users got into the habit of simplification. Also, the small systems tend to have higher frequency modes which don't have much effect on the rest of the structure. It also depends on what the model is being used for, if its for rough road durability then there's no need to model the headlining in any great detail, whereas if it was for interior noise they'd have to account for the headlining (but possibly with some sort of lumped model rather than as a piece of cloth and foam).

Cheers

Greg Locock


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