Is it compulsory to define a contact surface (point to surface) sequentially? For example, we should define the surface that is being hit first and then define the point that will hit the surface. Does meshing size effect when we use this surface contact (point to surface)? For example, the bottom surface meshing size should be bigger than the top size.
Just to clarify for everyone, you are referring to surface-to-surface contact in an MES analysis. The default setting is "Automatic" in which case the software will decide whether to use surface-to-surface contact or point-to-surface contact. In the case of point-to-surface contact, the Automatic will decide which part/surface will use the "points" (nodes) and which use the surface (face of the elements).
If you want to choose point-to-surface contact, which part/surface you choose for "points" depends more on the geometry and the interactionthan than on which part is moving and which is stationary. Perhaps this is what you are referring to when you wrote "surface that is being hit first and then define the point that will hit the surface".
The first part/surface that is chosen in the "Setup > Contacts > Surface-to-Surface Contact" dialog is the area that forms the "surface", and the second part/surface chosen in the dialog is the area that forms the "point".
Figure 2 on the wiki page "Surface-to-Surface Contact > Options" may help to clarify the differences between the selection order.
Simulation Mechanical user since Dec 1997