高温环境下板壳结构局部屈曲理论研究

Theoretical Investigation of Local Buckling of Plate-Shell Structures at Elevated Temperatures

关键词:  高温  板壳结构  局部热屈曲  后屈曲

Key words:  High temperature  Plate-shell structure  Local thermal buckling  Post-buckling

摘要:

传统高温板壳结构的热屈曲分析方法，在解决热-机械载荷耦合作用下复杂板壳结构的屈曲问题时存在较大的局限性，合理的局部热屈曲理论分析方法有助于提高板壳热结构设计水平。因此，根据高温板壳的结构特征和力学特征，在“机械载荷等效成局部边界压应力效应”假设前提下，提出了四种典型的应力等效的局部热屈曲模型，基于初始后屈曲渐近分析理论，建立了一套有效的局部热屈曲理论分析方法。采用上述方法，研究了完善和具有初始缺陷板壳的弹性热后屈曲性态，具体分析了带预载的四边简支模型，带预载的四边固支模型，带预载的三边简支、一边自由模型以及带预载的三边固支、一边自由模型，给出了板壳长度尺寸、厚度等参数对热屈曲载荷的影响规律，并将其推广到高阶热屈曲问题中。分析结果表明:板体现为分叉式屈曲，壳体现为跳跃式屈曲；在长宽比一定的情况下，长度越长，屈曲临界载荷越小，厚度越厚，屈曲临界载荷越高。

Abstract:

The traditional methods for analyzing the thermal buckling have the restrictions on dealing with the buckling of the complex plate-shell structures under the coupling of the thermal and mechanical loadings. The rational methods for analyzing the thermal buckling are conducive to improving the plate-shell design level. In the light of the above understanding，according to the structural and mechanical characteristics of high temperature plate-shell，under the hypothesis of the effects of the mechanical loadings equivalent to the local boundary stress，four kinds of local thermal buckling theoretical models were firstly proposed. The post-buckling behavior of the complete plate-shell and the one with initial defects were studied based on initial post-buckling asymptotic analysis theory. Pre-loaded four edge simple-supported model，pre-loaded four edges clamped model，pre-loaded three edges simple-supported one edge free model，pre-loaded three edges clamped one edge free model were studied in detail. The effects of structural geometry parameters (the length，thickness，etc.) on the post-buckling behavior of plate-shell structures were investigated and were extended to the solution of the high order thermal buckling problem. The results have shown that the buckling type of plate structure is bifurcation，and the shell structure’s is jumping. And under the constant length-width ratio，the critical load of buckling follows the rules that it decreases as the length increases while it increases as the thickness increases.