Effects of Concentrated Initial Stresses on Global Buckling of Plates

Buckling is an instability phenomenon that can occur if a slender and thin-walled plate — plane or curved — is subjected to axial pressure (e.g. inplane compression). At a certain given critical load the plate will buckle very sudden in the out-of-plane transverse direction. The destabilizing force could come from pure axial compression, bending moment, shear or local concentrated loads, or by a combination of these. If the structural element is bulky, the load-carrying capacity is governed by the yield stress of the material, rather than the buckling strength. If instead the element is slender and/ or thin-walled, the buckling strength is governed by the so-called slenderness ratio — the buckling length over the radius of gyration for global buckling of a column or a strut, or the loaded width over the thickness of the plate for local buckling. A special form of instability, that has to be considered with great care in design, is the combined global and local buckling risk of a slender and thin-walled axially loaded plated column — the capacity could be much lower than the two buckling effects analyzed separately. Conventionally, averaged initial stresses due to compression or shear are considered in a plate buckling analysis. Unfortunately, the analytical solutions of initial stresses for a cantilever square plate subject to uniform compression that the initial stresses concentrated at corners and cannot be considered uniform at all. The paper will report on the effects of concentrated initial stress on the global buckling of plates.