Nonparametric identification of nonlinear hysteretic systems

A nonparametric identification method for nonlinear hysteretic systems is p resented. Making use of the Duhem hysteresis operator, the multivalued rela tionship of hysteretic restoring force with respect to displacement and vel ocity of the phase plane is mapped onto two single-valued surfaces in an ap propriate subspace in terms of the state variables of displacement and hyst eretic restoring force. The functions describing the surfaces need not be s pecified in specific expressions, so that both the form and parameters of t he functions can be fine-tuned to match experimental results. They are iden tified by fitting the surfaces with the generalized orthogonal polynomials in terms of displacement and hysteretic restoring force. The proposed metho d is applied to the modeling of hysteretic behavior of a wire-cable vibrati on isolator from experimental data. Excellent agreement between the predict ed and experimental hysteresis loops is obtained. Based on the established hysteretic model, the dynamic response characteristics of a wire-cable isol ation system are evaluated.