The critical stress for a lipped plate of given geometry is normally found by solving a transcendental equation by numerical methods. By assuming that the minimum value of the buckling coefficient occurs when there is no transmission of shear loading from the lip to the flange, a solution can be obtained by a considerably simplified analysis. This is shown to give close agreement to the exact solution for a particular case. The simplified analysis allows the torsional stiffness of the lip to be taken into account; it can be applied to all lip shapes, and to many forms of constraint on the other longitudinal edge of the plate.
P.S. Bulson