| The general problem of plastic buckling of flat metal plates is a fundamental area of investigation in mechanics not only because of its intrinsic importance in the design of engineering structures, but also because it still has not been settled in a satisfying manner. Which theory of plasticity is the correct one to predict the buckling loads in the plastic range is a long-argued problem.;This thesis presents finite element analyses of plastic buckling and postbuckling behaviour of columns and plates, taking into account the presence of initial out-of-plane imperfections. The FE programs constructed by the author for this purpose are used to analyze the imperfection growth of such columns and plates under axial loading and simply supported edge conditions. The material behaviour is modeled according to both the incremental and the deformation theories of strain-hardening plasticity. The programs combine both the geometric and material nonlinearities to trace the load-deflection behaviours of these structures in prebuckling (up to the maximum load) as well as postbuckling ranges. The results of the analyses for plates show the extreme sensitivity of the incremental theory, and the relative insensitivity of the deformation theory, to the initial imperfections.;The programs are used to simulate the plastic buckling experiments on Aluminum tubes, taking into account their measured imperfections. The imperfection growth analyses demonstrate that the maximum load predictions of the incremental theory are quite close to those recorded in the experiments. |
