Further Research on the Effect of Test Machine Extentional Rigidity on the Initial Buckling Load of Unreinforced Circular Cylindrical Shells in Axial Compression

The inadequacy of the classical small displacement theory of thin shells in explaining the buckling phenomenom for circular cylindrical shells under axial compression and spherical shells under external pressure loading has long been established. Likewise it has become general belief that an explanation of their behavior can be given by means of a non-linear large deflection theory. The current interpretations of such theories when applied to these problems lean heavily upon a plausible but arbitrarily chosen energy criterion first given by Tsien, and predict that the initial buckling load of thin shells should be influenced by the testing machine stiffness. Two experiments described, statistically analysed and discussed by the authors in a previous paper revealed that test machine extensional rigidity does not to a high degree of probability influence the initial failing load of axially compressed cylinders. These results were obtained from repeated test on a single near perfect aluminum specimen and individual tests on many less perfect steel shells. They had R/t ratios of 313 and 226 respectively and buckled at 77 and 45 percent of the classical critical load.