Smart materials and structures have attracted a significant amount of attention for their vibration control potential in engineering applications. Compared to the traditional active technique, shunt damping utilizes an external circuit across the terminals of smart structure based transducers to realize vibration control. Transducers can simultaneously serve as an actuator and a sensor. Such unique advantage offers a great potential for designing sensorless devices to be used in structural vibration control and reduction engineering. The present literature combines piezoelectric shunt damping (PSD) and electromagnetic shunt damping (EMSD), establishes a unified governing equation of PSD and EMSD, and reports the unique vibration control performance of these shunts. The schematic of shunt circuits is given and demonstrated, and some common control principles and equations of these shunts are summarized. Finally, challenges and perspective of the shunt damping technology are discussed, and suggestions made based on the knowledge and experience of the authors.
Active vibration control of a cylindrical shell partially covered by a laminated PVDF actuator (LPA) is studied. The electromechanically coupled equations of the system are derived considering the influences of the bonding layers. The analytical expressions of the control forces induced by the LPA are obtained and thereafter a parametric study is conducted to evaluate the effects of the physical properties of the actuator on the control forces. The active vibration control of a clamped-free cylindrical shell using an LPA with different layer numbers is simulated and carried out experimentally. It shows that the control forces of the actuator can be significantly enhanced by increasing the PVDF layer number while keeping the driving voltage unchanged. As a result, the modal vibrations of the shell are suppressed quite well (the vibration amplitude is cut by 64.08%) under a relatively low control voltage (40 V) with a five-layer LPA whose area is only 0.21% of that of the shell. Additionally, as the LPA partially covers the shell surface along the circumferential direction, it can exert a radial actuating force on the structure except for the actuating moment, and the former is much larger than the latter and is thus preferable for controlling the structural radial vibration. To make full use of this actuating force, the actuator should not be placed at a point of large surface strain as is usual but at one of large radial deformation.
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