We study the dynamic behavior of a quartz crystal resonator(QCR)in thickness-shear vibrations with the upper surface covered by an array of micro-beams(MBs)under large deflection.Through taking into account the continuous conditions of shear force and bending moment at the interface of MBs/resonator,dependences of frequency shift of the compound QCR system versus material parameter and geometrical parameter are illustrated in detail for nonlinear and linear vibrations.It is found that the frequency shift produces a little right(left)translation for increasing elastic modulus(length/radius ratio)of MBs.Moreover,the frequency right(left)translation distance caused by nonlinear deformation becomes more serious in the second-order mode than in the first-order one.
The nonlinear behaviors of a circular-cylinder piezoelectric power harvester(CCPPH) near resonance are analyzed based on the flow-induced flexural vibration mode.The geometrically-nonlinear effect of the cylinder is studied with considering the in-plane extension incidental to the large deflection. The boundary electric charges generated from two deformation modes, flexure and in-plane extension, were distinguished with each other because the charge corresponding to the latter mode produces no contribution to the output current. Numerical results on output powers show that there are multivaluedness and jump behaviors.
A structure consisting of a spiral piezoelectric transducer and a concentrated mass is proposed as a low-frequency piezoelectric power harvester.A theoretical model is developed for the system from the theory of piezoelectricity.An analysis is performed to demonstrate the low-frequency nature of the system.Other basic characteristics of the power harvester including the output power,voltage,and efficiency are also calculated and examined.
