Split

You use the Split tab to apply fixtures or external forces to a section of a face instead of the whole face. The Split tab divides selected faces by either projecting a sketch on the selected faces, or by intersecting faces between two touching components.
Project a sketch on a face to create a split face.
Split a face by intersection. The two bodies must have touching edges or faces. To split the top face of the plate, first select the cylindrical face as a splitting face and the plate's top face as a face to split. The plate's top face splits into two faces.

Type of Split

Sketch Splits a face by projecting a sketch on it. You can use an existing sketch or click Create Sketch to create a new sketch. The sketch and the face to split must belong to the same body.
Intersection Splits a touching face between two bodies in contact. The two bodies must have touching edges or faces.

Selection

Project Sketch Lists the sketch you selected or created.
Other Faces to Split Select the faces to split.
Splitting face (Available when Intersection is selected). Select the intersecting face.
  Single direction Projects the sketch in only one direction.
  Reverse direction Projects the sketch in the opposite direction.
  Create Split Click to split the selected faces.