Ultimate strength of aluminium alloy outstands in compression: experiments and simplified analysis

Abstract An experimental investigation was undertaken to study the stability and ultimate strength of aluminium alloy outstands. In the tests, thin-walled cruciform aluminium extrusions were stressed into the post-buckling range in axial compression. The local buckling behaviour of the flanges of a cruciform section is the same as that of an outstand, i.e. a plate element which is free along one unloaded edge and simply supported along the other. Two tempers of alloy AA6082 with significantly different stress–strain curves were tested for five b / t ratios. The experimental ultimate strengths were compared with theoretical predictions, using the classical Stowell theory for plastic buckling in combination with the effective width concept, and with ultimate strength formulae recommended in the literature.