Nonlinear dynamic response of a wire rope isolator: Experiment, identification and validation

The vibration isolation capability of a nonlinear wire rope spring is experimentally and numerically investigated. The isolated structure consists of two cantilever beams with a lumped mass at the tip. The force-displacement cycles exhibited by the isolator show a hysteretic behavior due to interwire friction and geometric nonlinearities. The restoring force possesses a distinct nonsymmetry exhibiting softening under compression and hardening under tension. The device rheological response is identified using a suitable mechanical model to fit the experimental data. Families of frequency response curves (FRCs) for increasing levels of the vertical base excitation are obtained for the standalone device and the non-isolated and isolated structures, respectively. The comparison between the FRCs of the isolated and the non-isolated structures shows a severe reduction of the transmissibility coefficient in a broad frequency range. The proposed phenomenological model of the device, in which the parameters are identified according to the static response, is employed to predict the nonlinear dynamic response which also proves to be in good agreement with the experimental response.