Refined non-conforming triangular elements for analysis of shell structures

Based on the re"ned non-conforming element method, simple #at triangular elements with standard nodal displacement parameters are proposed for the analysis of shell structures. For ensuring the convergence of the elements a new coupled continuity condition at the inter-element has been established in a weaker form. A common displacement for the inter-element, an explicit expression of re"ned constant strain matrix, and an adjustable constant are introduced into the formulation, in which the coupled continuity requirement at the inter-element is satis"ed in the average sense. The non-conforming displacement function of the well-known triangular plate element BCIZ [1] and the membrane displacement of the constant strain triangular element CST [2] are employed to derive the re"ned #at shell elements RTS15, and the re"ned #at shell elements RTS18 is derived by using the element BCIZ and the Allmanʹs triangular plane element [3] with the drilling degrees of freedom. A simple reduced higher-order membrane strain matrix is proposed to avoid membrane locking of the element RTS18. An alternative new reduced higher-order strain matrix method is developed to improve the accuracy of the elements RTS15 and RTS18. Numerical examples are given to show that the present methods have improved the accuracy of the shell analysis. Copyright(1999 John Wiley & Sons, Ltd