Creo Simulate > Modeling Structure and Thermal Problems > Connections > About Connections
  
About Connections
A connection is the mating area between two or more parts or assembly components. Use the options on the Connections group on the Refine Model tab to create connections. When analyzing a part or assembly for which you have created connections, Creo Simulate uses the connection type and definition to determine the nature of the association between the connected areas.
You can create the following kinds of connections:
Native Mode
FEM Mode
For models in the native mode that include compressed midsurface shells, you must consider how you want Creo Simulate to treat mating and overlapping surfaces. When the surfaces of a component modeled with midsurfaces mate or overlap with the surfaces of another component, Creo Simulate creates automatic midsurface connections between all surfaces of the two components that are in contact with each other. Creo Simulate makes an exception for any surface where you explicitly create a weld, fastener, rigid link, or an interface.
After you create connections in the model, you can preview the different types of connections by clicking Home > Review Geometry in FEM mode or Refine Model > Review Geometry in native mode.
Links defined in the component, are propagated to the assembly. The coordinate system that the part refers to is transformed at the assembly level. That is, if a link refers to certain directions in the WCS of a part, then at the assembly level it refers to a UCS at the part WCS location.