Fully C1-conforming subdivision elements for ,nite deformation thin-shell analysis

We have extended the subdivision shell elements of Cirak et al. [18] to the ,nite-deformation range. The assumed ,nite-deformation kinematics allows for ,nite membrane and thickness stretching, as well as for large de9ections and bending strains. The interpolation of the undeformed and deformed surfaces of the shell is accomplished through the use of subdivision surfaces. The resulting ‘subdivision elements’ are strictly C-conforming, contain three nodes and one single quadrature point per element, and carry displacements at the nodes only. The versatility and good performance of the subdivision elements is demonstrated with the aid of a number of test cases, including the stretching of a tension strip; the in9ation of a spherical shell under internal pressure; the bending and in9ation of a circular plate under the action of uniform pressure; and the in9ation of square and circular airbags. In particular, the airbag solutions, while exhibiting intricate folding patterns, appear to converge in certain salient features of the solution, which attests to the robustness of the method. Copyright ? 2001 John Wiley & Sons, Ltd.