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Solid/Shell Error

Question asked by Matt Medford on May 13, 2011
Latest reply on May 18, 2011 by Bill McEachern

Using Simulation 2010, I'm running a static analysis of a clamp fixture (1/8th sector - see attached picture).  There are 4 bolts around the perimeter to hold the fixture together, and 5th bolt in the center which applies pressure to a plunger.  The plunger sandwiches a copper disk with a thin (.0003" thick) titanium foil.  You can't see the foil in the attached picture because it's so thin relative to the rest of the parts.  The loads in the bolts are accomplished by defining interference contacts at the bolt heads.  (Of course, this is a pain in SWX because you have to iterate on the bolt lengths - which requires bolt models of various lengths - until you get the right load values.  In Ansys, you would simply define the contact and change the interference as an option in the contact element.  Much easier to change a value in a dialog box than it is to "Replace Components".  But this is all a separate discussion and I'll get off my rant now...)

 

Most axial interfaces are defined as No Penetration.  The bolt thread contacts are bonded.  As mentioned, the bolt heads have intereference fits.

 

The foil is modeled as a surface-plane that is then converted to sheet metal with the .0003" thickness.  This then automatically meshes as a shell.  (If I model it as a solid, Simulation chokes on appying the symmetry constraints to the symmetry planes of the foil and also bungs up the meshing of the foil - obviously because the aspect ratio is so severe with such a thin element.)  When I try to Run the analysis, I get the attached cryptic error.  In addition to lousy English, it's difficult to make out what the error is suggesting to try to remedy the problem.

 

And, yes, it's necessary to have the foil in the analysis.  It's obviously too thin to contribute to the stiffness of the structure, but I need to look at how the pressure profile on the foil/copper interface changes when temperatures are applied (very different CTE's) and friction is considered.

 

I'd be much obliged for any suggestions and or commentary.

 

Thanks.

cryptic.jpgclamp-model.jpg

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