Coulomb friction oscillator: Modelling and responses to harmonic loads andbase excitations

In this paper we revisit a mass-spring-friction oscillator, where the frict ion refers to Coulomb's perfect dry contact friction. We refine the model f ormulation of the friction force and find that the equation of motion of th e oscillator is a two-phase linear system with a slide-stick switch, rather than the usual three-phases equations. Also we obtain a simple slide-slide condition. Then the exact solution of the response to simple harmonic load ing is obtained. With the aid of the long-term behavior of the exact soluti on, the steady motions of the oscillator with 0, 1, 2, 4, 6, 8, 10, 12, 14 stops per cycle are categorized in the parametric space of the ratios of fo rces and frequencies. Stops of zero duration are further classified into tw o types: normal stops and abnormal stops, the criteria of which are also gi ven. (C) 2000 Academic Press.