Local-Global Analysis for Plastic Collapse of Shells

壳结构的破坏通常是突然发生的，具有局部特征，并且几乎总是与失稳前或失稳后的塑性有关。研究的主要目的是建立一种分析模型，可用于研究这种局部壳的坍塌。虽然该模型最初是在旋转壳层的背景下开发的，但可以扩展到其他类型的壳层，并将详细说明。假定非线性只限于壳层的一个可定义区域。在该区域，将采用具有大挠度和塑性效应的一般四边形简并壳单元来捕捉变形的局部化。在其他地方，使用轴对称壳单元简单地描述了其行为。连接这些类型的元素是过渡元素，它们有“线节点”沿着它们的共同边界进入旋转壳元素和其他地方的点节点。动态分析将被纳入到跟踪snapthrough类型的崩溃，它总是伴随着塑性。预计该研究将对壳的局部破坏力学有新的启示，对壳结构的分析和设计技术具有重要的价值。

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.