How to Create a Midplane Mesh
For a CAD model with thin, solid features, using plate/shell elements to
model the thin features yields
a finite element analysis (FEA) model that has fewer elements and runs faster than modeling with solid elements.
You can use the midplane meshing capability to accurately model thin-walled geometry in less time with automatic handling of
parts, assemblies, multi-thickness regions and mixed-element-type models plus built-in gap healing where surfaces intersect.
As an example, consider the pole assembly shown in Figure 1. Modeling considerations included:
- The tube (blue) and base (red) parts of the assembly have a
thickness of 0.125" while the gusset parts (gray) have a thickness of 0.0625".
- For the gussets, the thickness is small relative to the length and width.
- The stress distribution through the thickness of the gusset parts should be linear.
It was decided to model the assembly using plate elements for the gussets and brick elements for the base and tube.
After opening the CAD model in the CAD Solid Model environment of FEMPRO,
mesh settings were specified for the entire model by using the "Mesh:Model Mesh Settings..." command sequence to access
the "Model Mesh Settings" dialog. In the "Mesh type" section, the default "Solid" option was left activated to specify that
all parts would be meshed with solid elements. This global mesh setting was used for the tube and base parts.
Figure 1: In the CAD Solid Model environment, the "Model Mesh Settings" dialog was
viewed to verify that the default "Solid" mesh type option was left activated to specify that the tube and base parts
meshed with solid elements.
Next, part mesh settings were specified for the four gusset parts. After selecting the gusset parts, a pop-up menu of options was
accessed by right-clicking in the tree view and the "Mesh settings:Parts..." command sequence was used to access the
"Part Mesh Settings" dialog. In the "Mesh type" section, the "Midplane" option was activated to specify that the selected parts
(the gussets) would be meshed with plate/shell elements (see Figure 2).
Figure 2: On the "Part Mesh Settings" dialog, the "Midplane"
mesh type option was activated to specify
that the four gusset parts would be meshed with plate/shell elements.
The "Mesh:Generate Mesh" command sequence was used to generate the mesh for the entire model. After meshing was completed, the
"View:Display:Mesh" command sequence was used to display the mesh, which showed that the tube and base were meshed with solid elements
and the gussets were meshed with plate/shell elements and matched to the solid elements (see Figure 3).
Figure 3: The final mesh shows that the tube and base parts were meshed with solid elements and the gussets were meshed with plate/shell elements.
Thus, the capability to specify mesh settings for both the entire model and individual parts, including midplane meshing
for thin parts, provides an easy and convenient way to mesh CAD models with thin-walled geometry. The resulting mesh
of combined solid and plate/shell elements has fewer elements and runs faster than a mesh with all solid elements.
For more information about midplane meshing, see the ALGOR User's Guide.