Menu: Geometry->Create->Contact surface
Contact surfaces are defined as being between two lines that are physically in the same place, but which have different line and point entities. From a contact surface, it is possible to generate contact elements, to be used by some calculation algorithms, which define a special contact between these two bodies.
Using contact surface entities is like a meshing specification. In this way, equal meshes will be generated for the two lines, ensuring a one-to-one relationship between nodes.
Choose the Contact surface option from the menu, and then select some lines on both bodies.
Contact elements are, by default, 4-node planar quadrilaterals. However, you can select 2-node lines for all cases (see Element type).
The 4-node planar quadrilaterals can be converted to the 8-node or 9-node for the quadratic case.
You can also select no mesh for the contact entity. This makes it possible to have exactly the same mesh for both lines but without any additional element between them.