2 Hole Concentration Factor

[stresscalcs]

I have recently seen an Airbus Excel spreadsheet that predicts the maximum Kt factor for two dissimilar diameter holes at variable distance and angle orientation in a plate for a uniform direct and shear stress conditions.

There is no reference to the source document for the calculation method.

An internet search has shown many documents with titles that sound interesting but without any way of actually seeing if they are relevant to finding the method. As they cost $20-$40, it would be very expensive to look at them all and perhaps find nothing.

Can anybody help by suggesting possible sources of information for the method? Perhaps it is Airbus "internal", thus not published.

Any help would be appreciated.

Stresscalcs

 

[ESPcomposites]

How about Peterson's Stress Concentration Factors? There is some data there.

If you don't have that, a free source is from my dissertation:

https://dspace.uta.edu/bitstream/handle/10106/767/umi-uta-1969.pdf?sequence=1

Starting from figure 5.3, there are various loading conditions and hole sizes. You will want to look at the (25/50/25) laminate, which is equivalent to an isotropic material.

There is additional raw data starting in Appendix C. In fact, it may be a better resource than Peterson since there are many raw verified raw data points.

Brian

http://www.espcomposites.com

 

[ESPcomposites]

P.S. If you are looking for a general method, rather than graphs, there is no "simple" solution. They will all need to have some numerical approach, such as the boundary collocation solution I used. An automated FEM solution would also be possible. I believe I discuss the options in the paper above.

Unless the holes get quite close or are very unequal, there is generally little interaction. That is for open holes though. Loaded holes are more "interactive", but that is another story.

Brian

http://www.espcomposites.com

 

[rb1957]

as Airbus is European, I expect they use ESDU more than the other side of the pond ...

 

[YoungTurk]

In addition to Peterson, ESDU 75007 is a good reference. It covers two holes with diameter ratio up to 1:10, for shear and normal stresses, but only for angles 0 / 45 ( / 135).