Local-Global Analysis for Plastic Collapse of Shells

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The collapse of shell structures often occurs suddenly, is localized in character, and almost always associated with plasticity in the prebuckling or post-collapse state. The major objective of the research is to develop an analytical model which can be used for the study of such localized collapse of shells. Though the model is to be developed initially in the context of rotational shells, possible extensions to other types of shells are in sight and will be spelled out. The nonlinearities are assumed to be restricted to a definable region of the shell. In this region, general quadrilateral degenerate shell elements incorporating large deflection and plasticity effects are to be used to capture the localization of deformation. Elsewhere the behavior is simply described using axisymmetric shell elements. Connecting these types of elements, are the transitional elements which have 'line nodes' along their common boundaries into rotational shell elements and point nodes elsewhere. A dynamic analysis is to be incorporated to trace the snapthrough type of collapse which is invariably accompanied by plasticity. It is anticipated that the research will shed some new light on the mechanics of localized collapse of shells and be of significant value in the technology of analysis and design of shell structures.