Frictional Contact

In the macroscopic view, contact forces comprise not only the normal forces that prevent interpenetrations but also tangential friction forces that dampen shearing motions at the interfaces. Most surfaces, when observed microscopically, are not perfectly smooth but are formed of jagged edges. Friction essentially arises from forces preventing non-interpenetration between these jagged edges. In this lecture, we introduce the Coulomb friction model, incorporating approximations that make it compatible with optimization time integrators.