Automatically morphing a mesh

Video: Morph a mesh after modifying CAD geometry

Use the Automatic Morph command to have the software try to automatically morph an existing mesh to conform to modified CAD geometry. During this process, the software tries to associate the existing nodes to the new geometry.

The Automatic Morph command is intended for cases in which the CAD geometry is modified but does not have any topological changes; that is there are no additions or deletions of vertices, edges, or faces. Additionally, any percentage in change to the CAD geometry, such as the length of an edge, should be relatively small.

Note:

As a best practice, you should use the Automatic Morph command immediately after you make a change to the CAD geometry.

Inspecting the topology prior to automatic morphing

In the Automatic Morph dialog box, you should first use the Inspect Topology option to check for:

• Topologically modified edges or faces.

• Nodes associated with those edges or faces.

Understanding the node movement options

In the Automatic Morph dialog box, you must specify the method that you want the software to use to move nodes on faces whose topology has been modified. Both methods control how the software moves the nodes as well as how it associates the nodes to the face. Both methods also work identically when there is no topology change.

• If you select the Move Based on Neighbor Movement method, the software moves a node based on how adjacent nodes move. It first disassociates all nodes located on topologically modified geometry. After the software moves the nodes, if any of the orphan nodes lies within the Association Tolerance value of its parent geometry (the geometry to which it was associated prior to the topology modification), the software: Projects the node back onto the geometry. Reassociates the node to the geometry.

• If you select the Move Keeping Association Intact method, the software uses the specified Association Tolerance value to determine how to associate and move nodes on topologically modified geometry during morphing. Nodes that lie within the Association Tolerance value to their parent geometry remain associated to them during morphing. The softare moves these nodes to the modified topology during morphing. Nodes that lie outside the Association Tolerance value are disassociated from the geometry before morphing. These nodes remain stationary during morphing. Note: This method does not work if the majority of nodes on any of topologically modified faces is not within the Association Tolerance value prior to morphing.

In the following graphic, (1) shows a simple model in which a face was moved and a blend was introduced.

(2) shows how the software moves the nodes using the Move Based on Neighbor Movement option.

(3) shows how the software moves the nodes using the Keep Association Intact option.

Element quality checking during automatic morphing

During the morphing process, the software automatically checks the quality of the affected elements using the quality checks specific to your solver environment. If it detects any elements that violate the quality threshold values, the software gives you the option to abort the morphing process. If you choose to continue, the software places those elements in an output group in the Simulation Navigator.

Automatic morphing in models that contain mesh mating conditions

In FEM files that contain mesh mating conditions, CAD modifications that do not cause a topology change may still modify the polygon geometry in regions where mesh mating conditions are defined. If you use the Auto Morph command in this type of model, the resulting mesh will likely not have 100% association between the nodes and the geometry. To identify regions where the nodes may be disassociated from the geometry, use the Inspect Topology options in the Automatic Morph dialog box prior to morphing.

Tip:

If you lose the association between the nodes and geometry after using the Automatic Morph command on faces that are part of mesh mating conditions, use the Node Association command to reassociate the nodes. Then, use the Automatic Morph command again. In most cases, this process restores the association between the nodes and the geometry.

Automatic morphing in models that have a seed 2D mesh or a surface coat mesh

There are special considerations for using the Automatic Morph command on models that have a 2D surface coat or seed mesh defined on top of a 3D mesh.

• If you select the 2D mesh for automatic morphing, the software morphs only the nodes in the 2D mesh. It does not morph the underlying interior nodes of the 3D mesh.

• If you select the 3D mesh for automatic morphing, the software morphs both the 3D and 2D meshes together.

Tip:

As a best practice, you should morph both the 2D mesh and the underlying 3D mesh together.

Automatic morphing and 2D dependent meshes

If you use the Automatic Morph on a mesh that was created using the 2D Dependent Mesh command, the software deletes the dependency between the master and the target surfaces. This means that if you use the Automatic Morph command to morph the master surface in the dependent mesh definition, the mesh on the target surface becomes an independent 2D mesh.

Automatic morphing in models that have manually modified polygon geometry

There are special considerations for using the Automatic Morph command on models where you have used polygon geometry modification commands, such as Delete Face or Merge Edge, to manually abstract the polygon geometry. Polygon geometry modification commands create and delete polygon geometry. This process can affect how existing nodes are associated to that polygon geometry. If you want to morph a mesh after you have manually modified the underlying polygon geometry, the Display Association capabilities in the morphing dialog boxes may not correctly display the node association.

To ensure that the association between the nodes and the polygon geometry is correct, you can:

1. Use the Automatic Morph command on the modified faces. This may not move any nodes, but during the automatic morphing process, the software may try to correct the node association. During this process, some nodes may become disassociated from the geometry even though they appear to lie directly on top of it. This is as designed.

2. Use the Node Association command to try to associate any orphan nodes to the appropriate polygon geometry.

3. If some nodes are still not associated to appropriate geometry, use the Manual Morph command to manually map the correct association between the orphan nodes and the polygon geometry.

Where do I find it?

Application	Pre/Post
Prerequisite	A FEM file as the work part and displayed part
Command Finder	Automatic Morph

Learn more

Morphing a mesh

Manually morphing a mesh

Morphing a revolved mesh

Comparing the manual morphing node distribution methods

Node and element association during morphing

Manually associating nodes to geometry

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Automatically morphing a mesh, Simcenter 3D 2021.1 Series

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