Shell Compression Error

[chris82]

I was able to run stress analysis on this thin walled feature
by utilizing the midsurface shell feature, but when I added the
ribs, I recieved an error message that said that the shell
couldn't compress. The ribs were created from on an offset
plane and exturded to the surface. Any suggestions?

Thanks.
P.S. I can't get the analysis to run without using shells, and am using Wildfire 3.0View attachment 4058

View attachment 4059

 

[chris82]

Sorry, those pics sucked. Here:

 

[chris82]

2007-08-22_185401_wing_for_analysis.prt.rar


another frustrating day of not being able to mesh elements. i'd appreciate it if someone took a look at this file and gave their input. version 3.0. thanks

 

[indigo2]

Chris -
I see a couple of issues. First, try to create the ribs as a thin protrusion, rather than a long thin rectangle. The sketch will be a single line, rather than 4 lines forming a rectangle. One advantage of thin protrusions is that they can be compressed automatically.

You could so the ribs as a single feature, or a set of individual ribs. I might prefer the latter, giving the option to optimize the location and size of each rib.

Secondly, take a look at the Geom Checks in the model. It appears that there is a _very_ small gap on the trailing edge, where the rib meets the trailing edge. That kind of thing will cause all sorts of issues with meshing, etc.

I think if you make those changes, you'll find the shell model should compress easily.
Hope that helps a bit.
-tsl