Skin Buckling and Stringer IDT

[P2FModder]

Hello there,

First time poster but been reading the forum for sometime now.

I would like to pick the expert's mind regarding Bruhn's methodology when it comes to skin buckling and stringer IDT. I have read the bruhn a few times regarding the IDT phenomena and I have not been able to find a clarity over this issue. Bruhn provides a formula to determine the diagonal tension load which needs to be added onto the existing stringer loads if the adjacent skin panels have buckled. However, it is unclear if we are required to spread the longitudinal loads from the skin panel into the stringer? Has this already been accounted for by the diagonal tension load formula?

In summary:
Bruhn's method: Total stringer stress = (stringer primary load / Area) + ( diagonal tension load / Area)
Do we need to do: Total stringer stress = (stringer primary load / Area) + ( diagonal tension load / Area) + (skin panel longitudinal * skin width / Area)

Please let me know what you think

Thanks

 

[SWComposites]

You need to read the post buckled stiffened panel effective width section. The load from the buckled skin area needs to be put onto the unbuckled skin + stiffener area.