Friction theory based on the subloading surface concept

A constitutive model for the description of friction phenomenon is formulated by incorporating the subloading surface concept proposed for the formulation of the unconventional plastic constitutive equation. It describes the nonlinearity of the relationship between the normal and the tangential forces on the contact boundary. Further, it describes the smooth relation of the contact force and the sliding distance, i.e. the smooth elastic-plastic transition and the thus the judgment for the fulfillment of friction condition is not needed, which is required in the conventional friction theory. Thus, a rough numerical calculation with large loading steps is allowed in the present model.