Honeycomb core panel analysis using Hexcel procedure - QUESTION

[Mines Mech E]

Greetings fellow stressors ... I need a little clarification:

I am doing analysis on an aluminum skin panel with Hexcel core (Trussgrid, density = 8.1 lbs/ft^3, Cell size = 1/8 inch). The panel is assumed to be simply supported on all four sides with a uniform pressure load. I am following the procedure defined in HexWeb Honeycomb Sandwich Design Technology Publication No. AGU 075b, Dec. 2000 (see link below) found on page 14-15 (Simply Supported Plate). Pages 16 and 17 provide graphs to determine the K-factors, K1, K2, and K3. The graphs include a sketch which clearly shows a rectangular plate defining the long side (a) and the short side (b). However, this sketch also indicates the core ribbon directions, Gw and GL. The panel I am analyzing has core directions opposite those indicated in the sketch - that is, Gw is along the short side (b) and GL is along the long side (a). My question is: what is the effect of core direction on the K-factor curves? Is there a different set of curves for K-factors when the core ribbon directions are opposite that shown in the document? If so, where can I get this set of curves?

Link to the Hexcel paper:

http://www.hexcel.com/Resources/Dat...eets/Honeycomb_Sandwich_Design_Technology.pdf

OR
I attached it to this post for download.

 

[Axoy_Design]

Hi,


Core (or ribbon) direction defines which shear modules you need to use when calculating the shear stiffness. You have Gw and Gl shear modules, and usually one is stiffer than the other based one the core pattern (ribbon direction). (Please check how the moment of intertia of geometrical shapes effects the bending stress, in this case hexagonal for most composite panels)
Here is a refernce

You can have the Gw and Gl from test/lab results. And use the lower value between the two when calculating your panel parameter(v). Once you have v value and you know your b/a ratio (length/width ratio) of your panel, then you can refer to those K-factor curves to find the K.


I don't think there is another K-factor curve chart. It all depends how you calculate your panel parameter(v) value (either using Gw or Gl whichever is less to be more conservative under certain loading condition.

http://www.axoydesign.com/

 

[VN1981]

Sorry for the late response. I hope you have found your answer.

One of the Aerospace OEM design manual states the following:

If Gxz = Gl and Gl > Gw; R=0.4
If Gxz = Gw and Gl > Gw; R=2.5
If Gl=Gw; R=1.0

If your project is industrial application where citing of reference is required, use the above with your own risk. Sorry, I cannot provide the reference document as it is proprietary.

 

[SAITAETGrad]

That is BDM-6710 if you can find or borrow it.