Static Friction Model of Elastic-Plastic Contact Behavior of Surface With Elliptical Asperities

The friction coefficient (mu) of a contact surface with elliptical asperities is examined at various values of the plasticity index (psi), the effective radius ratio (gamma), the shear-strength-pressure proportionality constant (c), and the dimensionless limiting interfacial shear strength (tau(m)). The results demonstrate that the friction coefficient of the contact system increases with an increasing value of gamma but decreases with an increasing value of psi. Furthermore, it is shown that Amonton's law is applicable for contact systems with either a low psi and a high tau(m) or a high psi and a low tau(m). Analyzing the ratio of the nonelastic contact area, it is found that the asperities of a surface characterized by a large gamma generally deform elastically at all values of the plasticity index, while those of a surface with a larger c deform plastically, particularly for surfaces with higher values of tau and psi. Finally, an inspection of the critical dimensionless real contact area shows that the contact mode of the surface is determined primarily by the value of the effective radius ratio.