Nonlinear shell models with seven kinematic parameters

We discuss design of nonlinear finite rotation shell model with seven kinematic displacement-like parameters, which are: three displacements of the middle surface, two rotations of the shell director, and two through-the-thickness stretching parameters. From the theoretical side we examine several possibilities for constructing the enriched kinematic field, which leads to different higher-order 7-parameter shell formulations. From the finite element implementation side a shell director interpolation is identified which eliminates the “curvature thickness locking”. Numerical examples are presented in order to compare different formulations and to illustrate the performance of the developed finite elements.