Free Interfaces
When you select Free as the type of interface, the connected components or surfaces may move freely relative to each other. The components may separate from each other or even interpenetrate each other. The applied forces do not transfer between the connected components or surfaces.
If you select the Split Surfaces check box, the connected surfaces split along the common boundaries. In the FEM mode, when you select the Split Surfaces check box on the Interface Definition dialog box, Creo Simulate generates a compatible mesh for the connected surfaces. In Native mode, Creo Simulate does not generate a compatible mesh for the connected surfaces.
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If the two surfaces connected by the Free interface are not compatible, you cannot select the Split Surfaces check box. Similarly, if the two surfaces are compatible but not coincident, Creo Simulate cannot split the surfaces in the native mode and displays a warning during meshing.