Curved shell finite elements for interlaminar stress analysis

A linear, first-order shear deformation shell theory is adapted to allow for large curvatures and through-the-thickness straining. The theory is applied to develop two types of shell elements for the analysis of strongly curved, thick, laminated composite structures: an isoparametric eight-node element and a novel curved four-node element. Both involve three translational and three rotational degrees of freedom per node plus a number of 18 and 9 internal strain parameters, respectively. Additionally, a simple and innovative technique for the evaluation of the through-the-thickness distribution of transverse normal and shear stress components has been developed, implemented within the element routines, and preliminarily tested.