Interaction between the effects of local and overall imperfections on the buckling of elastic columns

A. van derNeut has studied the buckling of elastic columns made from thin-walled members, with particular reference to the effects of imperfections. In this paper, a graphical method is used to extend his work and to make an exhaustive study of the combined effects of both ‘local’ and ‘overall’ imperfections. The resulting picture is remarkably simple, and the effects of imperfections are well described by the celebrated Perry formula in conjunction with a single imperfection parameter compounding simply the local and overall imperfections. Experiments on small-scale rubber model columns substantiate the main results of the theoretical analysis.