DYNAMIC VIBRATION ABSORBERS FOR REDUCING RESONANCE AMPLITUDES OF HYSTERETICALLY DAMPED BEAMS

摘要

The parameters of a viscously damped dynamic vibration absorber can be optimized to minimize a specific resonance of a structure. In this study, the optimum absorber parameters are found by solving a min-max problem (minimization of the maximum response in the frequency range of interest). The response of a structurally damped beam and absorber system is determined by the assumed-modes method. Harmonic excitations with constant and frequency-squared amplitudes are considered. The optimum parameters of the absorber suppressing the first or second resonance amplitudes of a cantilever beam are numerically determined and the results are presented in the form of non-dimensional graphs. The graphs are prepared for a given structural damping factor after studying the effect of structural damping on the optimum absorber parameters. The optimum absorber parameters found by this method are compared with those obtained by the approximate method employing an equivalent single degree-of-freedom system. It is demonstrated that the condition given in literature for the accuracy of the approximate method does not apply for the second resonance.