Modeling Honeycomb Panel using PSHELL/Stiffness Method in Nastran 1

[VN1981]

Hello,
I am heavily modifying my earlier post/thread (actually I prematurely deleted the earlier thread I had created).

Just to provide some background. I am analyzing a test case of an Titanium-Al Honeycomb Panel subjected to an uniform pressure with all sides simply supported. The facesheets are of Ti & the core is of 5052 Al.

Modeled the panel using 2D CQUAD elements with PCOMP (12I/T^3, Ts/T etc) definitions.

Up on further research, I found some miscalculations and omissions in my PSHELL definition and thus modified/updated the definition and reran the analysis.

I am getting fairly good agreement with hand calc values (< 5% difference) on peak deflection and facesheet stresses. However, I am unable to extract any transverse shear forces or stresses values from post-processor.

In the F06 file, I can see running Qx & Qy plate shear forces output.

How do I determine the core shear stress values, should I manually calculate the shear stresses from Qx & Qy values? Am I missing something?

- VN

 

[VN1981]

I guess I've found some answers to my question.

Going through the other threads about Honeycomb Panel modeling, it seems like with Pshell definition, the core shear stresses are not directly available in Nastran post-processor. For that feature, either the laminate has to be defined as a PCOMP layup and/or defining facesheets with 2d/3d elements & core with 3d brick elements.

So, I take it there is a need to calculate the core shear stresses separately from F06 outputs. Any recommendations on which program I can use? I found a reference to Laminator. I was unable to find any program named such on the web.

 

[VN1981]

I think I might have got a handle on core shear stresses. I selected elemental stresses output option and was able to get Qx & Qy out graphically. Divided the output by height of the core and got near target core shear stresses in L & W direction respectively.

If anyone is interested, I can do a detailed write up on the procedure followed so that the learning curve will be easier for other newbies.

 

[Wei24060]

I am pretty interested in this honeycomb structure modeling, any post would be much appreciated.

 

[VN1981]

Hi,
I will try to do a write up of the above procedure over this weekend or the next. If you are in a hurry, let me know and I'll see how much I can get it done during the coming weekend.

 

[dorbar]

Hi there!
Did you guys know about this s/w?
E-Xtreme's Digimat-HC

http://www.e-xstream.com/products/solutions/digimat-hc

Apparently it does a good job on constant thickens of honeycomb. Unfortunately my application has a different thickens over the span of a wing( thicker toward the fuselage and thinner toward the tip of a wing.
Anyhow I'm interested too, ...in any "interesting discovery" you might find

Cheers,D.

 

[dorbar]

Just slightly off-topic. I just found about Autodesk's Within s/w. It makes easy to design/analyze lattice structures! A real surprise for me, I have to admit . This is exactly what I need and with the event of 3D printing it makes honeycomb and other lattice structures more easy to design/make.
Within on Youtube:

https://www.youtube.com/watch?v=stPbmGpvCuw&feature=youtu.be

Please check this article too:

http://www.deskeng.com/de/composites-analysis-making-new-choices/