EQUAL-PEAK OPTIMIZATION OF DYNAMIC VIBRATION ABSORBER WITH NEGATIVE STIFFNESS AND DELAY FEEDBACK CONTROL

Compared with the traditional dynamic vibration absorber, negative stiffness dynamic vibration absorber has better damping capacity and wider effective damping frequency bandwidth. The time-delay feedback control is coupled into negative stiffness dynamic vibration absorber system to further reduce the amplitude of the resonant peak and increase the bandwidth of the effective damping frequency. In the present paper, the time-delay feedback control dynamic vibration absorber system with negative stiffness is designed by equal-peak optimization. The optimal design criteria are as follows: the peak values of the first and the second resonance peaks are equal; two objectives are considered at the same time, one is to optimize the maximum resonance peak amplitude to be less than the anti-resonance peak amplitude of the passive negative stiffness absorber system, and the other is to optimize the difference between the resonance peak and the anti-resonance peak to be less than the passive absorber system. Then, the equal-peak optimum design of the control system is carried out by designing and adjusting the negative stiffness coefficient, the damper coefficient of vibration absorber and the time-delay feedback control coefficient. Finally, the effect of structural parameters on effective damping frequency bandwidth is analyzed under the condition of reducing amplitude of resonant peak. A set of structural parameters are selected and compared with two typical models based on the results of equal-peak optimization. In order to quantitatively compare the reduction effect of different models, the amplitude reduction percentage is defined. It is found that the percentage amplitude reduction is over 40% in the effective damping frequency band. The results show that the percentage reduction of the resonance peak amplitude also approximates to 40% by optimizing the structural parameters and adjusting the gain coefficient and time delay. In addition, the amplitude-frequency response curve has wider effective damping frequency bandwidth and a lower difference between the amplitude of the resonance peak and the amplitude of the anti-resonance peak by adjusting gain coefficient and time delay.