Adaptive finite element buckling analysis of folded plate structures using variable-node flat shell elements

The finite element linear buckling analysis of folded plate structures using adaptive h-refinement methods is presented in this paper. The variable-node flat shell element used in this study (CLS, Choi and Lee, 1996) possesses the drilling D.O.F. which, in addition to improvement of the element behavior, permits an easy connection to other elements with six degrees of freedom per a node. Accordingly, the folded plate structures, for which it is hard to find the analytical solutions, can be analyzed using these developed flat shell elements. By introducing the variable-node elements, which have physical mid-side nodes, some difficulties associated with connecting the different layer patterns, which are common in the adaptive h-refinement on quadrilateral mesh, can be overcome. To obtain better stress field for the error estimation, the super-convergent patch recovery is used. The convergent buckling modes and the critical loads associated with these modes can be obtained. Analysis results of a few numerical examples are shown and compared with other researchers' results available.