In Finite Element Analysis, structures can be represented with a variety of elements including 0D, 1D, 2D and 3D elements. Thin walled structures are commonly represented with 2D or planar elements.
Different dimension elements can be used to represent the same geometry. An I-Beam (W Shape) can be idealized as 1D, 2D, or 3D elements.
Planar elements, also called two-dimensional (2D) elements, are used to represent a structure whose thickness is small compared to its other dimensions. Planar elements can model plates, which are flat, or shells, which have single curvature (e.g., cylinder) or double curvature (e.g., sphere). Planar elements can also be used to model sections that are uniform or non-uniform in thickness.
Below are various examples of thin structures and their respective midsurface representations.
Caption: Built up connection of an aerospace application
Caption: Injection molded plastics used in an automotive headliner
Caption: Machined rib used in aerospace applications
Caption: Injection molded plastic used in an electronic box
Caption: The midsurface is displayed within the original solid geometry
Caption: Wing tie used in aerospace applications
Midsurface Creation Process
A common way to produce a planar element mesh is to first create midsurface geometry that represent the midplanes of the thin walls and then mesh the midsurface geometry.
Caption: Midsurface Creation Process
Caption: Midsurface Creation Process for an Automotive Injection Molded Plastic