Attraction for mechanical systems with friction

The asymptotic behavior of systems with Coulomb friction represented as Lagrange’s equations of the second kind is investigated. Lyapunov’s direct method is used in combination with the method of limiting equations, which goes back to the works by G.R. Sell (1967) and Z. Artstein (1977, 1978) on topological dynamics of nonautonomous systems. The results generalize LaSalle’s principle of invariance.