...
In general, the contribution of shear deformation becomes significant when ratio between the span of plate-bending curvature and thickness is approximately 20:1 or 10:1. The formulation itself is adequate for ratio down to 5:1 or 4:1. In that this ratio is dependent upon the projected span of curvature, shell thickness may be greater than the actual plan dimensions of a shell object.
Stiffness for pure-bending
...
deformation
The statement that thick shells tend to be stiffer than thin shells applies only to the bending portion of the shell element deformation and for meshing that components of shells, and to models in which meshing is too coarse.
For a mesh which is adequate to capture When meshing adequately captures bending deformation accurately, the thick-shell element will be elements are more flexible because of the additional shear deformation due to shear that is not represented by the captured through thin-shell formulation. However, for Given pure-bending deformation, however, the thin-shell element is a little slightly more accurate, hence for coarser meshes therefore the thick-shell element may be stiffer . As for coarser meshes. This effect diminishes as the mesh is refined, this effect diminishes.
Stresses are more important may be of greater concern than deflections for most problems. Where When shear deformation can be is expected to be important, we recommend the thick-shell element because it will better capture the stress distribution. This is the case not only for thicker shells that are simply thicker, but also for regions near holes openings and other geometrical geometric discontinuities where in which transverse shear deformation develops.
...