Question : Buckling calculation using Tetmajers formula

I'm trying to calculate required diameter, buckling length or buckling force when
just one of them are unknown.

I have done this with the Euler approach sucessfully but run into problems
trying the same with Tetmajers approach.
Please see the attachment for more information.

Attachments:

TetmajerFormula.doc (34 KB) (File Type Details) 

Trying to solve for lk (buckling length)

Answer : Buckling calculation using Tetmajers formula

My bad, yes.. It is -ve :-)