Postbuckling Analyses of Elastic Cylindrical Shells Under Axial Compression

In designing a modern lightweight structure, it is of technical importance to assure its safety against buckling under the applied loading conditions. For this issue, the determination of the critical load in an ideal condition is not sufficient, but it is further required to clarify the postbuckling behavior, that is, the behavior of the structure after passing through the critical load. One of the reasons is to estimate the effect of practically unavoidable imperfections on the critical load, and the second reason is to evaluate the ultimate strength to exploit the load-carrying capacity of the structure. For the buckling problem of circular cylindrical shells under axial compression, a number of experimental and theoretical studies have been made by many researchers. In the case of the very thin shell that exhibits elastic buckling, experimental results show that after the primary buckling, secondary buckling takes place accompanying successive reductions in the number of circumferential waves at every mode shift on systematic (one-by-one) basis. In this paper, we traced this successive buckling of circular cylindrical shells using the latest in general-purpose FEM technology. We carried out our studies with three approaches: the arc-length method (the modified Riks method); the static stabilizing method with the aid of (artificial) damping especially, for the local instability; and the explicit dynamic procedure. The studies accomplished the simulation of successive buckling following unstable paths, and showed agreement with the experimental results.