Creo Simulate > Reference Links > Interfaces in FEM Mode
  
Interfaces in FEM Mode
In addition to end welds and perimeter welds, Creo Simulate uses interfaces to connect surfaces. When you create an interface, you specify how your surfaces will be treated during meshing and analysis. When you click Refine Model > Interface in FEM mode, the Interface Definition dialog box opens and display the following items:
BondedCreo Simulate considers two surfaces as bonded. This means that matching nodes on surfaces merge. Instead of two geometrically consistent nodes, a shared one exists unless you specify otherwise by selecting the Merge Coincident Nodes check box. Selecting this check box connects matching nodes with rigid link elements.
FreeCreo Simulate specifies two surfaces as contacting, but does not define the type of contact. Meshes on the surfaces are identical, and matching nodes are geometrically consistent unless you specify otherwise by clearing the Generate Compatible Mesh check box.
References—Use the selector arrow in this area and the regular selection methods to select two surfaces on your model that you want to define as Bonded or Free. You can select any two surfaces that you defined as mated or mated with offset in Creo Parametric. For more information on allowed surfaces, see Guidelines for Surface-Surface Connections and Interfaces (FEM mode). If you already selected valid surfaces before entering the dialog box, your selections appear next to the selector arrow when the dialog box appears.
Generate Compatible Mesh—This option is available only for Free interfaces, and is selected by default. If you clear this check box in the Properties area, Creo Simulate treats the surfaces on your interface as having no contact and does not create geometrically-consistent node locations when it generates the mesh for the surfaces. This is the same behavior as seen in previous releases for the None interface type.
 
* If you defined an interface type None for your assembly in a previous release, Creo Simulate converts the interface type to Free with the Generate Compatible Mesh option turned off. If you defined an interface type Free for your assembly in a previous release, Creo Simulate converts the interface type to Free with the Generate Compatible Mesh option selected.
Merge Coincident Nodes—This option is available only for Bonded interfaces, and is not selected by default. If you select this check box in the Properties area, Creo Simulate creates a rigid link element between each node on one surface and the corresponding node on the other surface. If you clear this check box, Creo Simulate considers the two surfaces as bonded. That is, nodes on the surfaces are shared between the meshes of the parts.
 
* In case of the contacting surfaces moving away from each other because of shell compression, Creo Simulate cannot process the Bonded interface, without you selecting the Merge Coincident Nodes option. This is because of the absence of coincident nodes.
You can set either Bonded or Free as the default contact type for FEM mode. In this case, Creo Simulate applies the default you set to all mated surfaces in your model except those for which you explicitly define a different type of contact. You can set the default contact type on the Creo Simulate Model Setup dialog box.
 
* In native mode, the Free connection type is not supported as a default setting. If you define the default connection type for your assembly as Free in FEM mode, and open the assembly in native mode, any analysis you run will use a default connection type of Bonded.