Assumed Strain Finite Element Shell Formulations

Efficiency, generality and simplicity of use have ensured the continued popularity of degenerated shell elements [1]. The basic assumptions employed in degenerated shell elements are similar to those used for Mindlin plate elements [2]. Ahmad degenerated a three-dimensional brick element into a general curved shell element which has nodes only at the midsurface. The stress in the thickness direction is assumed to be equal to zero and the element displacement field is expressed in terms of three displacements of the midsurface, two rotations of the midsurface “normal” and appropriate shape functions.