During a study of the dynamic characteristics of a wire rope vibration
isolation system constructed with helical isolators, an interesting i
nstability was observed. Following an experimental investigation of th
is system, a semi-empirical model having non-linear stiffness, nth pow
er velocity damping, and variable Coulomb-type friction damping was de
veloped. Results obtained using ACSL compare well with experimental da
ta. The primary emphasis of this paper, however, centers on the instab
ilities and large-response behavior of this semi-empirical model. Stab
ilizing effects are discussed.