Setting Spring Constant To Surface

Setting Spring Constant To Surface

alex.robertsE9DNR
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Setting Spring Constant To Surface

alex.robertsE9DNR
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I am trying to model a steel assembly that will be supported by a rubber (or something similar) pad that allows some growth downward. Is there a way to set a spring constant or spring connector to a whole surface instead a point to distribute the load? 

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John_Holtz
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Hi @alex.robertsE9DNR 

 

I think it would be easier to model the elastic support and bond your model to it.

 

Otherwise, you need to edit the Nastran file and manually add one spring and constraint to each of the nodes that you want to support. It is probably not too hard if you have access to the Nastran Editor Utility. I would add 1 spring to the model so that the Nastran file has the commands for the spring and constraint. Then you have a pattern to use when defining all of the other springs.



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


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Message 3 of 4

alex.robertsE9DNR
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Hi @John_Holtz 

 

For modeling my elastic support- Do default materials have the ability to deform like this or will I need to make a custom material?

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Message 4 of 4

John_Holtz
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The main difference between modeling the piece of rubber and using separate springs at every node is that the modeled component is all connected together, whereas the individual springs are all individual. If you the analysis could somehow magically compress only some of the springs but not all of the springs, then

  • using a part with a load on a fraction of the surface still compresses most of the surface.
  • using individual springs would compress only the springs with the load.

Of course, most situations that I can think of are not like the individual springs example because the real rubber pad is a continuous block (or however you model it). The real pad is not individual volumes at each node and unrelated to the neighbors.

 

Of course, you have a known stiffness, so you need to adjust the material properties of the modeled pad to duplicate that stiffness. Otherwise, choose the material that best fits the behavior of your support. (In other words, isotropic material type because like a regular material, hyperelastic material type allows for large stretch, and so on.)

 

 



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


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