Node Merge is a mesh editing tool that enables you to merge mesh nodes within a specified tolerance, making the mesh conformal across bodies, parts, and assemblies. Node merge can be used in conjunction with Node Move to remove large gaps in meshes without degrading mesh quality significantly. Node Merge can be performed on solid, sheet, and line bodies.
Scoping
Similar to Mesh Connections, Node merges are performed on mesh nodes. You must, however, explicitly specify the tolerance for node merges. Node merges can be face-to-face, face-to-edge, or edge-to-edge. Node Merge is a post-mesh operation, performed after the base mesh is generated. The base mesh is then stored so that if you change a node merge, only local re-meshing is required to clean up the neighboring mesh.
Requirements
For a Node merge to be successful, the mesh must be of similar size, and the number of mesh nodes to be merged on both topology entities need to be equal. If nodes on the primary and secondary do not have a 1–1 correspondence, then the resulting mesh after node merge can have holes.
Note: Mesh Connections take priority over Node Merge operations. If nodes are connected by mesh connections, then the Node Merge operation will ignore the connection.
Application
Node merge operation supports two methods for connecting the mesh: Automatic and Manual. They both work similarly, with the exception that in manual node merge the node merge objects are explicitly populated in the tree, but are hidden in automatic mode. Automatic node merge is very useful when working on very large assemblies, as large number of node merge objects can slow down performance. Manual node merge, however, allows you to review individual node merge objects in detail.
A node merge operation is executed as a single operation on the base mesh of the whole model. If you have multiple node merge groups, executing Generate on a single group will merge only the nodes in that group, and will return the mesh to the state prior to the node merge operations on the other groups. To connect all of the node merge groups, execute Generate at the Mesh Edit folder level.
If you have applied any mesh connections or contact matches, you should generate them before applying node merges.
To automatically apply node merges:
Right-click the Model object in the Tree and choose Mesh Edit, or select the Model object and choose Mesh Edit from the Model toolbar.
Right-click the Mesh Edit object and choose>, or choose Node Merge Group from the Mesh Edit toolbar.
Select the Node Merge Group and set the Method to Automatic Node Merge in the Details view (this is the default setting).
Set the Scoping Method to Geometry Selection (the default) or to Named Selection and choose the body or bodies to search for node merges.
Modify the Tolerance settings in the Details view. The Tolerance value is used to find which bodies should be connected to which other bodies. For a discussion of Tolerance settings, see Tolerances Used in Mesh Connections, although Snap Boundaries are not available for Node Merges.
Tolerance Type: Options include , , and . Bodies in an assembly that were created in a CAD system may not have been placed precisely, resulting in small overlaps or gaps along the connections between bodies. You can account for any imprecision by specifying connection detection tolerance. This tolerance can be specified by value when the type is set to and , or sheet thickness of surface bodies when the type is set to .
Tolerance Slider: Appears if Tolerance Type is set to . To tighten the connection detection, move the slider bar closer to +100 and to loosen the connection detection, move the slider bar closer to -100. A tighter tolerance means that the bodies have to be within a smaller region (of either gap or overlap) to be considered in connection. A looser tolerance will have the opposite effect. Be aware that as you adjust the tolerance, the number of connection pairs could increase or decrease.
Tolerance Value: Appears if Tolerance Type is set to or . This field is read-only if the Tolerance Type is set to showing the actual tolerance value based on the slider setting. When the Tolerance Type is set to , you can provide an exact distance for the detection tolerance.
After you provide a greater than zero value for the Tolerance Value, a circle appears around the current cursor location. The radius of the circle is a graphical indication of the current Tolerance Value. The circle moves with the cursor, and its radius will change when you change the Tolerance Value or the Tolerance Slider. The circle appropriately adjusts when the model is zoomed in or out.
Use Range: Appears when the Tolerance Type property is set to or . Options include and (default). If set to , you will have the connection detection searches within a range from Tolerance Value to Min Distance Value inclusive.
Min Distance Percentage: Appears if Use Range is set to . This is the percentage of the Tolerance Value to determine the Min Distance Value. The default is 10 percent. You can move the slider to adjust the percentage between 1 and 100.
Min Distance Value: Appears if Use Range is set to . This is a read-only field that displays the value derived from: Min Distance Value = Min Distance Percentage * Tolerance Value/100.
Face/Face: Options include and (default). Detects connection between the faces of different bodies. The maximum allowable difference in the normals for which contact is detected is 15 degrees.
Face/Edge: Options include and (default). Detects connection between faces and edges of different bodies. Faces are designated as targets and edges are designated as contacts. Saying Yes exposes Face Angle Tolerance and Edge Overlap Tolerance.
Edge/Edge: Options include (default) and . Detects connection between edges of different bodies.
Search Across: This property enables automatic connection detection through the following options:
Bodies (default)
Parts: Between bodies of different parts, that is, not between bodies within the same multibody part.
Anywhere: Detects any connections regardless of where the geometry lies, including different parts. However, if the connections are within the same body, this option finds only Face/Face connections, even if the Face/Edge setting is turned On.
Face Angle Tolerance: Available only if Face/Edge is set to Yes. For faces that will be excluded from the proximity detection pair, this property defines the minimum angle between the primary face and secondary edge entity, above which the two face pairs will be ignored from proximity detection. The default value is
70°.Edge Overlap Tolerance: Available only when Face/Edge is set to Yes. This tolerance value is the minimum percentage that an edge may overlap the face and is included as a valid proximity detection pair. The default value is
25%.
Generate the node merge by doing one of the following:
To... Do this... Generate all node merges Right-click Mesh Edit and choose . Generate node merges for a Node Merge Group For each Node Merge Group that should not be generated, right-click the Node Merge Group and choose .
Right-click the Node Merge Group and choose .
To manually apply Node Merges using the Node Merge Group:
Right-click the Model object in the Tree and choose Mesh Edit, or select the Model object and choose Mesh Edit from the Model toolbar.
Right-click the Mesh Edit object and choose>Node Merge Group, or choose Node Merge Group from the Mesh Edit toolbar.
Select the Node Merge Group and set the Method to Manual Node Merge in the Details view.
An additional control, Group By is exposed in the Details view. Options for Group By include , , and , and . This property allows you to group the automatically generated connections objects. Setting Group By to (default) or to means that connection faces and edges that lie on the same bodies or same parts will be included into a single connection object. The Faces option is only available if the Face/Face or Face/Edge controls are set to Yes.
Setting Group By to None means that the grouping of geometries that lie on the same bodies or same parts will not occur. Any connection objects generated will have only one entity scoped to each side (that is, one face or one edge). If there are a large number of source/target faces in a single region. Choosing None avoids excessive contact search times in the solver.
Right-click the Node Merge Group and select Detect Connections. The states of the Node Merge connection are denoted using the same symbols as are used for Mesh Connections.
Generate the node merge by doing one of the following:
To... Do this... Generate all node merges Right-click Mesh Edit and choose . Generate node merges for a Node Merge Group For each Node Merge Group that should not be generated, right-click the Node Merge Group and choose .
Right-click the Node Merge Group and choose .
Generate individual node merges Select each node merge that you want to generate, right-click, and choose .
To manually apply Node Merges individually:
Right-click the Model object in the Tree and choose Mesh Edit, or select the Model object and choose Mesh Edit from the Model toolbar.
Right-click the Mesh Edit object and choose>, or choose Node Merge from the Mesh Edit toolbar.
The object is added as a child of a new Node Merge Group.
Alternatively, you can select a Node Merge Group and set the Method to Manual Node Merge in the Details view. Then, right-click the Node Merge Group and choose >.
Set the Scoping Method to Geometry Selection (the default) or to Named Selection to determine how you will select the Primary Geometry and Secondary Geometry.
Select the Node Merge object and choose the Primary and Secondary Geometries:
“Primary” indicates the topology that will be captured after the operation is complete.
“Secondary” indicates the topology that will be pinched out during the operation.
Set the controls under Definition as desired.
Generate the node merge by doing one of the following:
To... Do this... Generate all node merges Right-click Mesh Edit and choose . Generate the individual node merge Right-click the node merge and choose .
Note: The mesher does not check the quality of the mesh after a Node Merge is performed. Therefore, you should perform a manual quality check any time you insert a Node Merge.