Dong Jingshi

Analysis on sucking process outflow phenomenon of piezoelectric pump

The sucking outflow phenomena of a passive piezoelectric pump under the square wave driving is studied and a hydrodynamics model and a vibration model of the passive piezoelectric pump are built to analyze theoretically the physical process of the sucking outflow process.Then,an open height formula of the exiting valve in sucking processing is derived.The open height of the piezoelectric pump is measured during the sucking outflow process under different frequencies of 0.4,0.8,6,45 Hz,and the other factors effecting on the sucking outflow in the formula are verified.In the theoretical analysis,it points out that the flow inertia is the root cause for the outflow sucking phenomena,and the inertial flow also exists during the draining process.The experiment indicates that when the piezoelectric frequency increases,the open height of the exiting valve during sucking process decreases.When the exiting valve rigidity and the loadings in input and output increase,the outflow decreases.The results above are coincident with the formula well.It concludes that the output flow of the piezoelectric pump should include two parts: cubage flow and inertial flow,which should be considered in the same time when the flow of the piezoelectric pump is controlled precisely.

Study on active vibration control technique based on cantilever beam

In order to solve the contradiction between lightweight and noise of a vibrating cantilever beam, active control actuated by piezoelectric ceramics is presented in this study. The dynamic model of the cantilever beam is established by finite element method (FEM). The piezoelectric actuator excited by control signal is bonded near the fixed end of the cantilever beam to suppress the beams first vibration mode. The control signal is collected by a sensor and processed by the quadratic optimal control theory. Experiment results show that the amplitude of the active controlled cantilever beam is reduced to 48.2% than the uncontrolled one under constant external excitation.

Notice of Retraction Modeling and optimum design of a rectangular piezoelectric vibrator for multi-degree-of-freedom motor

Multi-degree-of-freedom (DOF) motors have become more and more useful in the complex electromechanical system. Multi-DOF motor composed of plate type piezoelectric vibrator is compact and easy to miniaturize. In this paper, simulation and finite element analysis of a multi-DOF motor with a rectangular piezoelectric vibrator as the stator are presented. The finite element model of the piezoelectric vibrator is established to analyze its vibration type under the B32 and B23 working modes. The main structural dimensions of the piezoelectric vibrator, including the aspect ratio and the thickness of the rectangular substrate, the width and height of the protrusion, are analyzed by computer simulation, which demonstrates the relationships between these structural parameters and the amplitude and the modal frequency of the piezoelectric vibrator. The principles to determine these structural dimensions are presented thereby.