Nonlinear, buckling and postbuckling analysis of shells of revolution.

摘要

This thesis presents a series of developments leading to an efficient and accurate finite element analysis for nonlinear, buckling and postbuckling behaviour of thin elastic hells of revolution. An accurate isoparametric doubly-curved axisymmetric shell element is employed in these developments, with circumferential variations of loads, deformations and internal forces all represented by Fourier series. The work represents an important step towards the eventual development of a so-called 'advanced analysis' for stability design of steel shell structures in which imperfections, residual stresses and material plasticity are all realistically modelled.; A limited number of analyses have been developed for nonlinear shells of revolution under arbitrary loads. A number of deficiencies are identified in existing studies. Among these are the uncertainty concerning the accuracy of existing nonlinear shell theories, the inability to trace the descending part of the load-deflection path of unsymmetrically loaded shells when the pseudo-load concept is used, and the lack of efficient and powerful techniques to predict postbuckling responses with mode switching.; A study on suitable nonlinear strain-displacement relations for numerical analysis of complex branched shells is first described.; A large deflection analysis of axisymmetric shells and plates on a nonlinear tensionless elastic foundation is presented in this thesis.; A new finite element formulation is then presented for the nonlinear and collapse (limit point buckling) analysis of elastic doubly-curved segmented and branched shells of revolution subject to arbitrary loads.; Post-bifurcation buckling analysis of shells of revolution subject to axisymmetric loads is a key to understanding their postbuckling behaviour and imperfection sensitivity.; Finally, the finite element formulation for perfect shells under arbitrary loading mentioned earlier is extended to shells with non-symmetric imperfections. The initial imperfections are also arbitrary and expanded into truncated Fourier series. As a special case of this analysis, the imperfection-disturbance method is presented for tracing complex postbuckling paths involving mode switching and interaction. In addition, the imperfection sensitivity of a number of problems is examined using the developed analysis. (Abstract shortened by UMI.)