Geometry abstraction, polygon geometry, and convergent geometry > Suppressing holes in polygon sheet bodies

Suppressing holes in sheet bodies

Some models may contain holes which have little impact on its overall stiffness. In analyses in which you are interested in the overall behavior of a structure and not the stresses in the vicinity of the holes, you may want to ignore selected holes to eliminate unnecessary mesh density. You can use the Suppress Hole command to remove holes from sheet bodies, such as midsurface sheet bodies. You can remove:

Selected holes or all holes whose diameter is smaller than a specified threshold value.
Holes contained within a single face.
Holes that span multiple faces.
Circular and non-circular holes.

When the software removes the hole, you can optionally choose to create either a point or a mesh point at the hole’s center of gravity. You may want to create a mesh point at the hole’s center, for example, so you can later create an FE-based connection element, such as an RBE2, at that location.

You can use the Suppress Hole command either before or after you create a mesh on the part. If you use Suppress Hole to remove holes from a face that you have already meshed, you can use the Update Finite Element Model command to update the mesh.

Suppression works for both circular and non-circular holes

You can use the Suppress Hole command to remove both circular and non-circular holes from your model.

The following graphic shows an example of how you can use Suppress Hole to automatically remove a number of holes at one time. (A) shows a 2D mesh on a midsurface sheet body that contains a series of 4 mm holes . The Suppress Hole command was used to remove all holes with a diameter smaller than 5 mm. (B) shows the updated mesh on the sheet body.

You can also use Suppress Hole to remove non-circular holes from your model. In the case of non-circular holes, the software uses the perimeter of the hole as the basis for suppression. For a non-circular hole, the software computes the equivalent diameter as follows:

the equivalent diameter of a non-circular hole = the perimeter of the hole/π

For a non-circular hole, you enter the equivalent diameter value in the Hole Diameter box in the Suppress Hole dialog box.

The following graphic shows how you can use Suppress Hole to automatically remove both circular and non-circular holes. (A) shows a 2D mesh on a body panel. We then used the Suppress Hole command to remove all holes with a diameter smaller than 375 mm. (B) shows the updated mesh.

Unsuppressing holes

After you suppress a hole, you can use other Model Cleanup commands to unsuppress that hole. You first use the Split Face command with the Split face by suppressed edges option to unsuppress the edge that defines the perimeter of the hole. You then can use the Repair Face command to remove the face inside the perimeter of the hole.

The following graphic shows an example of unsuppressing holes. (A) shows the edges that are currently suppressed. The Split Face command with the Split face by suppressed edges option was used to unsuppress the highlighted edges. (B) shows the updated mesh with the unsuppressed edges.

(C) shows the updated mesh after the Repair Face command was used to remove the face on the inside of each hole’s perimeter.

Replay of automatic hole suppression after updates to geometry

The software stores information suppressed holes in the CAE Geom Recipes node in the Simulation Navigator. If the CAD geometry in either the master or the idealized part is updated, the software uses the recipe to try to re-suppress the holes when the FEM file is updated.

CAE Geom Recipes
1 – holes in belt top side
2 – holes in belt bottom side

The software stores recipe information about a suppressed hole when:

The CAD part associated with your FEM file is loaded at the time you use the Suppress Hole command.
The hole is contained within a single face. The software does not create recipes for suppressed holes that span multiple faces. If the CAD geometry updates, you must re-suppress those holes manually.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM file active
Command Finder	Suppress Hole
Menu	Model Cleanup→Suppress Hole

Quick links

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