Use of the Southwell method to predict buckling strengths of stringer stiffened cylindrical shells

This paper presents the results of some tests that were conducted on stringer stiffened epoxy cylindrical shells. The object of the investigation was to determine if the Southwell technique for estimating buckling loads could reasonably be used for the nonlinear collapse of cylindrical shells. The results showed that the technique provides a useful estimate of the buckling load provided care is taken in interpreting the results. In some instances the estimate is likely to be greater than the actual load. Where two buckling modes are encountered at the same time the Southwell technique appears to predict the critical load associated with either mode depending on the deflection parameter being measured as well as on the interpretation of the results.