Numerical studies of the conventional impact damper with discrete frequency optimization and uncertainty considerations

This paper presents the performance of a single horizontal conventional Impact Damper (ID) in both wide range frequency and resonance excitations. The effects of the coefficient of restitution, e, mass ratio, , and clearance, d, on the performance of ID are investigated. The optimal parameters are numerically found by discretely varying the clearance and excitation frequency. The performance of optimal ID is discussed, with respect to different parameters, in both resonance and off-resonance modes. In addition, it is shown how the efficiency of the optimal conventional ID is deteriorated as a result of mistuning in the amplitude and frequency of excitation. This is estimated by suggesting a new criterion of post processing data. It is shown that an ID designed to resist high amplitude excitation is able to perform well at lower amplitude. However, the opposite trend can significantly deteriorate the efficiency of optimal ID. In regard to excitation frequency, the ID, optimized with respect to a wide range of frequency, is less sensitive to frequency mistuning. Finally, the vulnerability of the optimized ID versus uncertainties in structural parameters is clearly determined and it is illustrated that less robustness occurs when the performance of the controller is more efficient.