A system for the vibration suppression in the broad frequency range using a single piezoelectric actuator shunted by a negative capacitor

A system for the vibration suppression using a single piezoelectric actuator is presented. The method is based on the fact that the transmission of vibrations between two objects can be reduced through an extremely soft element, which is placed between those objects. It is also known that by connecting a negative capacitor to the piezoelectric actuator it is possible to create an element whose elasticity can be arbitrarily tuned. Therefore, by combining these two principles, a new vibration control system, which consists of a piezoelectric actuator connected to a negative capacitor, has been realized. High efficiency of the vibration transmission suppression is achieved when the amplitude and phase of the piezoelectric actuator impedance matches (except the sign) the amplitude and phase of the negative capacitor impedance. The frequency, at which the both dependencies are intersecting, can be controlled by adjustable circuit elements of the negative capacitor. Every single setting of the negative capacitor parameters is optimal just for one corresponding frequency of the incident vibrations. In the case of vibration suppression in a broader frequency range, the frequency dependence of the negative capacitor capacitance has to match the frequency dependence of the piezoelectric element capacitance within the entire considered frequency range. By one single optimal setting of the negative capacitor parameters can be efficiently suppressed the transmission of vibrations with several harmonic components or with a random component. Two difficulties have been solved in the presented realization: first, the electronic arrangement that allows the extremely accurate adjustment of the negative capacitor circuit parameters and, second, the principle which allows achieving exactly the desired frequency impedance characteristics of the negative capacitor. It is shown that such an arrangement allows the realization of a simple and compact system, which, however, offers great vibration isolation efficiency in variable vibration conditions.