FURTHER RESEARCH ON THE EFFECT OF TEST MACHINE EXTENTIONAL RIGIDITY ON THE INITIAL BUCKLING LOAD OF UNREINFORCED CIRCULAR CYLINDRICAL SHELLS IN AXIAL COMPRESSION,

摘要

The inadequacy of classical small displacement theory of thin shells in explaining buckling phenomenon for circular cylindrical shells has long been established. Likewise,it is general belief that an explanation of their behaviour can be given by means of non-linear large deflection theory. The current interpretations of such theories when applied to these problems lean heavily upon the 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 analyzed 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 tests on a single near-perfect aluminum specimen and individual tests on many less perfect steel shells. They had R/t ratios of 313and 226respectively and buckled at 77and 45percent of the classical critical load. Two additional experiments using the single special approach described in detail in this report supplement and extend the authors previous research by considering circular cylinders with higher R/t ratios which buckled at a lower percentage of the classical critical load. The results provide overwhelming evidence that the Tsien criterion is inapplicable in all problems considered. The consequence,however,is the same; a new look at the large displacement analysis and the appropriate criterion is needed. (Author)