Electro-mechanical dynamic analysis of the piezoelectric stack

Considering a piezoelectric stack to be connected with structures at both ends in order to sense or control the relative displacement or velocity between structures, the electro-mechanical behavior of the stack as a sensor, actuator, vibration isolator and absorber is analysed in detail. Analytical results show that it is possible to apply the piezoelectric stack as a velocity sensor. Meanwhile, when it is employed as an actuator, its actuating force and electric admittance considerably change with the variation of the impedance of the two connected structures. Moreover, the results demonstrate that the isolation and suppression of structural vibration could be realized by the direct method, where velocity of controlled structures is directly annihilated by counter-action of the piezoelectric stack imposed by an external electric field, and the active damping method, where structural velocity is attenuated by the increase of the damping coefficient induced by the stack. However, the results also illustrate that induction of the positive active damping coefficient by the stack with the feedback of sensing electric current is conditional for the suppression of structural vibration while it is unconditional for isolation of vibration. This implies that it is not always possible in the whole frequency range to suppress the structural vibration with the active damping method: on the contrary, instability of structural vibration could be triggered.