Highlights

Linear eigenvalue buckling with a geometric stiffness built from the membrane stress of every element
Lowest positive load factors with a verdict on the first, and mode shapes in 3D coloured by amplitude
Takes the meshed model from an open ShellFEA tab and saves it as a project, on your computer or cloud
Three samples with closed-form answers: plate in compression and in shear, cylinder under axial load
An independent count confirms no factor is missing; linear buckling is stated as an upper bound

A question it answers

At how many times its design load does this stiffened tank wall first buckle, and in which shape?

What you put in

A ShellFEA model (sent from ShellFEA's Run panel, or taken from an open ShellFEA tab with From ShellFEA: mesh, materials, thicknesses, seams, supports, loads), a sample model or a saved project; the number of modes.

What you get

The lowest positive buckling load factors with a verdict on the first, the reversed-load root when the model is in tension, mode shapes in 3D coloured by amplitude, the pre-buckling minimum principal membrane stress, the share of elements in compression, free DOFs, iterations and, for a sample, the difference from its closed form; and a line that says whether an independent count confirms the list — no factor below the first, none missing up to the last.