Nondestructive method to predict the buckling load in elastic spherical shells

This paper presents a general methodology for predicting the critical buckling loads of spherical shells using a nondestructive test. For this purpose, the well known graphical method of predicting buckling loads, i.e., the Southwell's nondestructive method for columns is analytically extended to spherical shells and a new formula is derived for the critical buckling load of uniformly compressed spherical shells. Subsequently, finite element simulation and experimental work proved that the theory is also applicable to spherical shells with an arbitrary axi-symmetrical loading as well. The results show that the technique provides a useful estimate of the elastic buckling load provided care is taken in interpreting of the results. The usefulness of the method lies in its generality, simplicity and in the fact that, it is non-destructive. Moreover, it does not make any assumption regarding the number of buckling waves or the exact localization of buckling.