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gfraulini17-Peridot
17-Peridot
March 26, 2014
Solved

Fasteners on symmetry plane

  • March 26, 2014
  • 9 replies
  • 5009 views

Hi all,
if I want to analyze an assembly with the symmetry constrain I need to "cut" the entire assembly before to enter in Mechanica.
But if the cut is passing trough a hole where I want to put a screw with the fastener proE feature, I can't; because that feature needs an entire circle and not only one half.
In this case what I do?
In each case, the preload force of a screw, cutted at half from the symmetry, should be the half?

Regards


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Best answer by 346gnu

Hi,

You cannot 'cut' a fastener idealisation in half.

If you have a symmetry plane that passes through the fastener then you have to mode the fastener as a solid.

Regards

9 replies

346gnu13-AquamarineAnswer
13-Aquamarine
March 26, 2014

Hi,

You cannot 'cut' a fastener idealisation in half.

If you have a symmetry plane that passes through the fastener then you have to mode the fastener as a solid.

Regards

gfraulini17-PeridotAuthor
17-Peridot
March 26, 2014

How can I set a preload force modeling the screw as a solid?

I suppose I need to set a free contact region between screw and hole.

Can you explain better this concept, please?

I have this assembly, already simplified for the FEM analysis.

It is an equipment testing.

I need to see the displacement (especially the vertical one) ander the mass load of the components.

Some components are suppressed and replaced directly with their forces.

The symmetry plane is named TAGLIO; there is the symmetry of geometry and loads.

sdensberger2-Explorer
2-Explorer
March 28, 2014

I believe you said in your other thread that you're using WF5 (I'm not too sure if this feature was added in), but there is a pre-load for solid elements.

Preload.png

If this feature isn't in WF5, then you could make your fastener out of beams and links (or solid elements) and use a temperature load to cause the fastener to go through thermal contraction. This will be an iterative process to ensure that you've got the correct pre-load (just like with the fastener tool). Make sure that you restrict the thermal load to just the fastener (you don't want the result of the model to contract), or define a material property on the rest of your system that has a zero coefficient of thermal expansion.

gfraulini17-PeridotAuthor
17-Peridot
April 14, 2014

Nobody else have never tried something like this and can give some suggestions?

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