Exclusion of a component

[gfraulini]

Hi all,
happening to have one or more component of an assembly that you don't want include into the analysis because, for example, it is so much rigid respect the others. At the same time you don't want eliminate that component beacose the force is trasmitted trough it or it represents a mass.
Anyway, if I want maintain the componet in the simulation, how can I do?
If I put on it a Control of "Isolate for Exclusion" ?

How would you do?
Regards

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[neomechanikos]

I've done this before by adding a point mass at the CG of the part to be removed and then attach it to the part. If the part transfers a load, I've modeled the connections of the point using beam idealizations and making them very stiff. I suppose you could use isolate for exclusion but I've never used it for that purpose...might be difficult to get what you want.

[gfraulini]

However putting on the component the control of exclusion should lighten the resolution of the system of equation because the program does not search the solution on the nodes of that component; I think this means the program does not include the equations relative these nodes, so it should be much faster.

What do you think?

[neomechanikos]

Yes, it will be faster. It limits the polynomial order, and excludes them from some results calculations if you tell it to do so in the analysis properties. It just might be difficult to define the entire part as excluded. I am curious to know how well it works.

[sdensberger]

Isolate for Exclusion is a mesh control used for convergence. Specifically, it tells the software to exclude the selected from consideration in the convergence study. The only way this could help you speed up your study is if you restrict the p-order in the analysis definition AND if it so happens that software would drive the p-order of the element after the first pass.

That being said, what type of analysis are you doing and what results are you after? While you could go through the process or replacing a component with a idealized representations, it may be faster to just leave it in the model (depending on what you're doing).

[gfraulini]

I need to do an analysis on a testing equipment and I want to see how many millimeters it moves vertically.

Since the structure has many screws and some component where I'm not interested verify the displacemet, I've asked the right manner for simulate the fastener and pieces that I can suppose rigid; these pieces "rigid", I can't substitute them whit an idealization, beacose they serve as support for some screws.