A 9-NODE ASSUMED STRAIN FINITE-ELEMENT FOR LARGE-DEFORMATION ANALYSISOF LAMINATED SHELLS

An application of the element-based Lagrangian formulation is describe d for large-deformation analysis of both single-layered and laminated shells. Natural co-ordinate-based stresses, strains and constitutive e quations are used throughout the formulation of the present shell elem ent which offers significant implementation advantages compared with t he traditional Lagrangian formulation. In order to avoid locking pheno mena, an assumed strain method has been employed with judicious select ion of the sampling points. Three strictly successive finite rotations are used to represent the current orientation of the shell normal. Th e equivalent natural constitutive equation is derived using an explici t transformation scheme to consider the multi-layer effect of laminate d structures. The are-length control method is used to trace complex l oad-displacement paths. Several numerical analyses are presented and d iscussed in order to investigate the capabilities of the present shell element. (C) 1998 John Wiley & Sons, Ltd.