Bidirectional energy-controlled piezoelectric shunt damping technology and its vibration attenuation performance

Piezoelectric material-based semi-active vibration control systems may effectively suppress vibration amplitude without any external power supply,or even harvest electrical energy.This bidirectional electrical energy control phenomenon is theoretically introduced and validated in this paper.A flyback transformer-based switching piezoelectric shunt circuit that can extract energy from or inject energy into piezoelectric elements is proposed.The analytical expressions of the controlled energy and the corresponding vibration attenuation are therefore derived for a classical electromechanical cantilever beam.Theoretical predictions validated by the experimental results show that the structure vibration attenuation can be tuned from−5 to−25 dB under the given electrical quality factor of the circuit and figure of merit of the electromechanical structure,and the consumed power is in the range of−13 to 25 mW,which is a good theoretical basis for the development of self-sensing,self-adapting,and self-powered piezoelectric vibration control systems.

Investigations of thickness-shear mode elastic constant and damping of shunted piezoelectric materials with a coupling resonator

Shear-mode piezoelectric materials have been widely used to shunt the damping of vibrations where utilizing surface or interface shear stresses. The thick-shear mode （TSM） elastic constant and the mechanical loss factor can change correspondingly when piezoelectric materials are shunted to different electrical circuits. This phenomenon makes it possible to control the performance of a shear-mode piezoelectric damping system through designing the shunt circuit. However, due to the difficulties in directly measuring the TSM elastic constant and the mechanical loss factor of piezoelectric materials, the relationships between those parameters and the shunt circuits have rarely been investigated. In this paper, a coupling TSM electro-mechanical resonant system is proposed to indirectly measure the variations of the TSM elastic constant and the mechanical loss factor of piezoelectric materials. The main idea is to transform the variations of the TSM elastic constant and the mechanical loss factor into the changes of the easily observed resonant frequency and electrical quality factor of the coupling electro-mechanical resonator. Based on this model, the formular relationships are set up theoretically with Mason equivalent circuit method and they are validated with finite element （FE） analyses. Finally, a prototype of the coupling electro-mechanical resonator is fabricated with two shear-mode PZT5A plates to investigate the TSM elastic constants and the mechanical loss factors of different circuit-shunted cases of the piezoelectric plate. Both the resonant frequency shifts and the bandwidth changes observed in experiments are in good consistence with the theoretical and FE analyses under the same shunt conditions. The proposed coupling resonator and the obtained relationships are validated with but not limited to PZT5A.

Singular variation property of elastic constants of piezoelectric ceramics shunted to negative capacitance

Piezoelectric shunt damping has been widely used in vibration suppression, sound absorption, noise elimination, etc. In such applications, the variant elastic constants of piezoelectric materials are the essential parameters that determine the performances of the systems, when piezoelectric materials are shunted to normal electrical elements, i.e., resistance, inductance and capacitance, as well as their combinations. In recent years, many researches have demonstrated that the wideband sound absorption or vibration suppression can be realized with piezoelectric materials shunted to negative capacitance. However, most systems using the negative-capacitance shunt circuits show their instabilities in the optimal condition, which are essentially caused by the singular variation properties of elastic constants of piezoelectric materials when shunted to negative capacitance. This paper aims at investigating the effects of negative-capacitance shunt circuits on elastic constants of a piezoelectric ceramic plate through theoretical analyses and experiments, which gives an rational explanation for why negative capacitance shunt circuit is prone to make structure instable. First, the relationships between the elastic constants c11, c33, c55 of the piezoelectric ceramic and the shunt negative capacitance are derived with the piezoelectric constitutive law theoretically. Then, an experimental setup is established to verify the theoretical results through observing the change of elastic constant c55 of the shunted piezoelectric plate with the variation of negative capacitance. The experimental results are in good agreement with the theoretical analyses, which reveals that the instability of the shunt damping system is essentially caused by the singular variation property of the elastic constants of piezoelectric material shunted to negative capacitance.

Modeling and analysis of cantilever beam with active-passive hybrid piezoelectric network

The active-passive hybrid piezoelectric network (APPN) is investigated to reduce the vibration of cantilever beam. Hamilton's principle with the Rayleigh-Ritz method is used to derive the equations of motion of the beam with the APPN. Only one piezoelectric actuator is bonded on the cantilever beam, so in the segment of the beam where the piezoelectric actuator is attached, the neutral axis is not the geometric center of the beam. This change on the neutral axis is considered in the process of deriving equations. Selecting RL circuit as passive shunt circuit, open-loop analysis is performed to gain insight into the passive damping features. Velocity feedback control is then employed to analyze the characteristics of the closed-loop system. Numerical results show that the APPN has a significant effect on vibration suppression, especially at narrow frequency bands. On this basis, variable RL circuit is proposed and analyzed for broadband vibration attenuation. Numerical simulations illustrate that this scheme is effective and feasible.