Which element formulation is appropriate when working with a model having a thickness-to-span ratio of greater than 0.05?

When considering the thickness-to-span ratio of a model, it is important to choose the correct element formulation to accurately capture the behavior of the structure. A thickness-to-span ratio greater than 0.05 indicates that the shell is not sufficiently thin, which necessitates the use of a thick shell element formulation.

Thick shell elements are designed to accommodate the effects of through-thickness shear deformation and are more appropriate for models where the thickness is significant relative to the span. These elements take into account the variations in stress and strain across the thickness of the shell, allowing for a more realistic simulation of the material behavior under loads.

Using a thin shell element formulation in this scenario would not adequately model the behavior of the shell structure because such elements typically assume that shear deformations are negligible, which is not valid when the thickness is relatively large. Therefore, thick shell element formulation is the correct choice for ensuring accurate simulation and analysis of structural performance under specified conditions.