Attachment
The Attachment node is used to define a set of edges on a flexible shell which can be used to connect it with other components through a joint in the Multibody Dynamics interface. All the selected edges behave as if they were connected by a common rigid body.
Attachments can be added to boundaries in a Multibody Dynamics or a Solid Mechanics interface, to edges in a Shell or Layered Shell interface, or to points in a Beam interface. This makes it possible to use a joint in the Multibody Dynamics interface for connecting parts modeled in different physics interfaces.
The Attachment node is available with the addition of the Multibody Dynamics Module. The use of attachments is discussed in the Attachments section in the Multibody Dynamics Module User’s Guide.
Location in User Interface
Context Menus
 Shell>Connections>Attachment
Ribbon
Physics tab with Shell selected:
Edges>Connections>Attachment