Creating Gaps (FEM Mode)
The
Gap Definition dialog box opens when you click
Refine Model >
Gap. Use the
Gap Definition dialog box to create one or many gaps.
The Gap Definition dialog box includes these items:
• Name—Enter a descriptive name or accept the default name.
• References—Select geometric entities on your model. You can create a point–point, point–edge, point–surface, or surface-surface contact.
If you already selected valid geometric references for a gap before opening the Gap Definition dialog box, your selections appear in the collector when the dialog box opens. Otherwise, select the relevant geometry.
For a Point-Point, Point-Edge (Projection), or Point-Surface (Projection) gap, you can select any of the following entities.
◦ Single point or vertex
◦ Point feature (includes one or more single points)
◦ Pattern of point features
◦ Two points or vertices
◦ Single point and an edge or a vertex and an edge
◦ Single point and a surface or a vertex and a surface
For a Surface-Surface gap, you can select any of the following entities:
◦ Surfaces on two different parts in an assembly
◦ A surface and a quilt on the same part
◦ Surfaces with the same type of curvature. For example, you cannot form a surface-surface gap between a planar surface and a spherical surface, or a cylindrical surface and a cone surface.
• Orientation—Define the Y direction by selecting a datum point, edge, curve, axis, surface, or vertex to identify the XY plane of the element. You can also specify a vector in the WCS.
The X direction represents the gap length, which is the shortest distance between the two selected references. A zero-length gap has no length between the two references. For example, you can define a gap between a point on a surface and the surface itself. For such a zero-length gap, the X direction is normal to the surface.
• Properties—Define the stiffness properties which include the following:
◦ Distribution—Select the method that Creo Simulate uses to calculate the axial and transverse stiffness for your gap. The stiffness are distributed uniformly across the surfaces.
|  The Distribution option is available only if you select Surface-Surface as the reference. |
◦ Total—The entered value represents the sum of stiffness for all gap elements.
◦ Per Unit Area—The entered value is multiplied by the surface area to give the stiffness values. The area of the first selected surface is used for the stiffness calculations. See
Surface-Surface Gaps for more information.
◦ Clearance—Define the distance between two nodes at which Creo Simulate applies the axial and transverse stiffness due to displacement during an analysis. If you specify Clearance as zero, the gap acts as a spring.
◦ Axial Stiffness—Define the axial stiffness value. This parameter defines the stiffness or a spring factor. The default value for this parameter is 0.
◦ Transverse Stiffness—Define the transverse stiffness value. This parameter defines elastic stiffness, characterizing resistance of the material until the slippage occurs. The default value for this parameter is 0.
After you create a gap, you can edit or delete it as follows:
• Editing a gap—On the Model Tree, right-click the gap icon that you want to edit and click Edit Definition to re-open the Gap Definition dialog box and edit the current settings. You can also double-click the specific gap to edit it.
• Deleting a gap—On the Model Tree, right-click the gap that you want to delete and click Delete on the object action menu or press DEL.
You can control the visibility of gaps on your model by changing settings on the
Simulation Display dialog box, by using the
search tool, or by placing them on
layers.