Properties of equal bodies in contact with friction

The properties of a reduced friction model for elastic bodies with general surfaces in contact are explained, and it is proved that the tangential friction problem can be reduced to the normal problem. The tangential solution results as the difference of the full slip traction for actual contact and a smaller contact area, which represents the stick area (or multiple areas). The local traction in the slip area opposes the relative motion in the same way as the normal relative approach opposes the contact pressure, as required by Coulomb’s slip inequality. The stick inequality for the traction is identical with the contact condition of positive pressure. A superposition method for general loading scenarios is explained and an example is calculated at the end. The force displacement relation of the reduced friction model agrees well with the FEM solution, even for dissimilar materials, because the dissimilarity effect is small in practical applications. Since numerical solutions of frictional contact are rare in literature, an example for a contact area with a hole is presented.