Direct stiffness method analysis of shells of revolution utilizing curved elements.

A doubly curved axisymmetric shell element is constructed for use in the analysis of shells by the direct stiffness method. The new element is expected to remedy difficulties experienced with the conical shell element, developed by Grafton and Strome and extended by Percy et al., in the case of shells subjected to distributed loadings. The curved element provides a highly accurate approximation to the shapes of shells of revolution with arbitrarily curved meridians. Numerical illustrations of the shape approximations are given for spherical and elliptical shells. The direct stiffness method equations are derived, and calculations are given for the case of an internally pressurized spherical shell. Comparisons of these results with those provided by the conical element are presented and discussed.