Equivalent Viscous Damping for Systems with Friction-Affected Constraints∗

For a multibody system with friction-affected constraints, responses with the same period as the harmonic excitation are considered. Equivalent viscous damping factors are defined, with the requirement that the systems with friction and viscous damping have the same oscillation amplitudes. Accelerations and reaction forces of the system with friction and equivalent damping are compared. Significant differences become evident which suggest that viscous damping concepts provide only a vague equivalence for motion resistances due to friction.