36. Development of a Tuning Algorithm for a DynamicVibration Absorber with a Variable-Stiffness Property

In this study, we propose a frequency estimation method based on an adaptive line enhancer algorithm to be used for changing the property of the frequency-tunable dynamic vibration absorber. This method estimates the frequency from the time series of the delayed input signal, focusing on the fact that the autocorrelation function of noise converges rapidly to zero when the phase difference for several sampling periods is set. An elastomer composite with controllable stiffness, known as a magnetorheological elastomer, is used in a dynamic vibration absorber whose natural frequency is tuned adaptively to the disturbance frequency through the application of an external magnetic field. Firstly, we explain the structure of a variable-stiffness absorber and the mechanism of the proposed frequency tuning algorithm. Secondly, the test result of the absorber properties, namely, the natural frequency and damping ratio, is shown. By taking full advantage of the frequency adjustability of the proposed vibration absorber, we then evaluated the real-time vibration control performance for an acoustically excited plate having multiple resonant peaks. The sweep excitation tests show that the vibration of the structure can be effectively reduced with an improved performance by using the adaptive-tuned dynamic vibration absorber to be used with the proposed frequency estimation algorithm.