Modeling the Unsymmetric Hysteretic Loops of Friction-Type Isolators

The friction-iype vibration isolalors exhibit nonlinear hysteresis under cyclic loading or dynamic excitation. They display unsymmetric hysteretic behavior in the unsymmerric conjguration or with static preloading. In the present paper, three improved BoaWen models are presented to describe the unsymmemc hysteresis loops offiictionrVPe isolators. The corresponding nonlinear poramerric identification procedure is developed on the basis of periodic vibration tesests by imposing cyclic sinusoidal motion of specified amplirudes and frequencies. The proposed models and poramerric idenfification procedure hove been applied to model the unsymmerric hysteresis loops of a wire-cable isolator from the experimenral displacement and restoring force records obtained in the compressiontension mode. The case shady illustrates how lo delermine the appropriare model in virtue of experimenrally obtained hysteresis curves and illustrates the skill in implementing the porameMc idenlification procedure lo actual hysteretic isolators.