EQUIVALENT VISCOUS DAMPING MODELS OF COULOMB FRICTION IN MULTI-DEGREE-OF-FREEDOM VIBRATION SYSTEMS

摘要

Friction is difficult to model in multi-degree-of-freedom mechanical systems. Experimental studies of damping in vibrating mechanical systems typically use modal damping factors to represent the damping. Energy lost by friction is included in these factors. This paper presents an analysis of the friction energy dissipated by each mode to derive several models of equivalent friction modal damping. These friction damping factors can be subtracted from the overall modal damping factors when doing computer simulations where the dynamic friction forces are calculated directly. In order to verify whether the equivalent friction damping models are reasonable, a two degree of freedom system is simulated using three approaches: a piecewise continuous analytical method, numerical integration with a spring-damper friction model, and numerical integration with equivalent friction damping. Five cases with periodic and non-periodic excitation are considered. The equivalent friction damping works very well for cases where sliding motions predominate; for long periods of sticking, the overall motions are predicted well but the detailed motions are approximated. (C) 1995 Academic Press Limited [References: 15]