Taking the deformed model out of Simulation (FEA) and using it!

Article by Wayne Chen, CSWP updated May 16, 2011

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Let’s see what we can do with the simulation deformed model.  It can be saved as a new solid model shown below.

In this example I will take a cushion from a sofa and deform it by making a dummy sitting on it.

I downloaded the models from 3D Content Central:

Combining them in a new assembly.  Make sure the model is simple enough for FEA.  Below is what I end up with:

Make sure the butt is touching the cushion so FEA won’t complain about model unstable.

Now in the study, I would like to mention a few boundary controls (BC’s from this point forward) and setup.

The cushion is fixed at the bottom so it does not move at all.  As for the material, I modified the plastic PE material and made it softer (lower elastic modulus).  For the dummy material, I used something harder (higher elastic modulus).  The density of the dummy is increased for the study purpose.  Gravity is added so the denser dummy will push the cushion and deform it.  No penetration contact set is created between the bottom faces of the dummy and the top surface of the cushion.

Adding a reference geometry constraint so the dummy only moves in the same direction as gravity.

Mesh control on the possible contacting surfaces.  This is for the smooth deformed shape in the result.

Run the study with draft quality mesh to make sure I did not miss any BC’s and make sure the model is stable.

Run the study in high quality mesh.  Hide the dummy to show the deformed shape of the cushion.

Right click on the results folder and select “create body from deformed shape”.  You have a choice to create a new file or a configuration of existing file.  I generally use new file so the original stays untouched.  Now a few things may happen when this command is used:

– successfully created a body (desired outcome)

– created body has spikes, weird shape surfaces, or invalid geometry

– SW terminates

For the last 2 outcomes, you will need to go back to the model, and simplify the bodies if possible (get rid of unwanted tiny features and details).  Also check if finer mesh is utilized on important details, and where it will deform the most in the model.  It took me a few times to correctly export the deformed shape.

 

 

 

 

 

 

Above is the deformed shape of the model.  One can take this model and do some further analysis, or for some other purposes.

Some people would like to generate point cloud from the deformed model.  Save the model in STL format (in the save as option, you can change the resolution of the output, the finer it is, the more cloud points you have), activate ScanTo3D (under SW Premium license), and open the STL using file type: mesh.  Next, save the file as point cloud file.

Above is the cloud point file opened in SW.

Hope you enjoyed this article!

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Wayne Chen, CSWP