連続体を対象とした速度フィードバック加振の影響の解明

抄録

Experimental modal analysis is a well-established technique for understanding the vibration characteristics of mechanical structures. However, it is difficult to identify the modal characteristics of high damping structures, because the resonance peak of the frequency response function (FRF) in the high frequency range cannot be clearly captured and the number of modes to be adopted cannot be accurately determined. Therefore, this study proposes a method to clearly capture the resonance peak of FRF using velocity feedback excitation, which cancels the influence of damping. Specifically, a control circuit for velocity FB is designed and shaking experiments are conducted based on the control system. The proposed method was validated by conducting excitation on a continuum and confirming that the effect of damping is reduced. The control circuit for the velocity FB control was designed to doubles the amplitude when the input signal is 500 Hz. In excitation experiments on beams using this control circuit, the effects of damping on multiple vibration modes were reduced and the resonance peaks were clearly captured. But, reducing the effects of damping on all vibration modes was difficult, because the resonant frequencies of the shaker were in the frequency range of the target. Hence, by applying velocity feedback excitation considering the characteristics of the exciter, the influence of damping on the target vibration mode can be reduced. The proposed method is expected to accurately identify the modal characteristics of vibration modes whose response peaks do not clearly appear.