Theoretical Investigation Of Piezoelectric Actuator And Resonant Piezostack Dirven Gas Micropump

As an important part of the Micro-electro-mechanical system,Micro flow system has been the essential component of Micro refrigeration system.Piezoelectric acutators have been extensively studied in the fields of biological fluid handling、thermal management of electric component and aerospace fields,because its advantages such as fast response,low power consumption,small size and high energy density.More and more scholars have been researching on it.Through the mathematical methods,the operating mechanism differences of piezoelectric membranes and piezostack micropumps are discussed.The impacts of the voltage,the radius ratio and the thickness of piezoelectric and elastic layer on the displacement of circular piezoelectric diaphragm are also investigated.By analyzing the influence of different parameters,the structure design of a circular piezoelectric actuator is optimized and the resonant frequency of a piezoelectric actuator is also decreased.Besides,a resonant piezostack driven gas micropump is researched on the different voltages and frequencies、mass and pressure loads.In the end,the operation model of piezostack micropumps is built to analysis the displacement and the pressure varing with the time.The pressure and mass flow of the piezostack micropumps can be calculated by theoretical model.Through the theoretical analysis,the resonant gas micropump can satisfy the pressure and the mass flow of micro refrigeration system.The main works of this study are as following:(1)Combined with the theory of circular plate and piezoelectric constitutive equation.The analytical model for piezoelectric actuators has been established by analysis strain and bending moment in the different radius of piezoelectric actuator and the analytical solution for membrane deformation is also provided.The results are compared with literature experiments and simulations on the same geometric parameters and material properties.The relative error is less than 10%,from which the analytical model is validated(2)The effect of different parameters on the deformation of piezoelectric actuator has been analyzed.The displacements of circular piezoelectric actuator linearly varies with the voltages.When the thickness and the material property are fixed and the radius ratio of piezoelectric layer and elastic layer is 0.75,the center displacement of circular piezoelectric actuator obtains the maximum.The thickness of piezoelectric layer and elastic layer has different effect on the deformation of piezoelectric membrane.Especially the thickness of piezoelectric layer.When the thickness of the multi-layer is fixed,the optimal thickness ratio of piezoelectric layer and elastic layer is 0.45-0.48(3)The characteristic value method is used to calculate the resonant frequency of piezoelectric actuator,combined with the results of theory and experiment,the effects of the radius ratio of piezoelectric layer and elastic layer and the thickness of elastic layer to resonant frequency are also discussed.(4)When the gas pressure is taken into the dynamic model,a new analytical model of piezostack driven gas micropump is established to discuss the effect of gas pressure to the dynamic system.The pressure of gas has strongly effects on the performance of piezostack driven gas micropump.Combined with the results of theory and literature experiment,the resonant frequency is increased with the gas pressure raise and decreased with the mass increases.To ensure that the resonant frequency is the same,the mass gain/gas pressure difference is 3.3,the magnification of the mass displacement and gas pressure rise radio is also decreased with the increased gas pressure.(5)The operation model of pizostack driven gas micropump is built to analysis the displacement of the mass and the gas pressure varying with time under different voltages and different frequencies.In particular,it focuses on the pressure rises and mass flow of the resonant gas micropump.Compared the performance of piezostack driven gas micropumps with the different voltages and the different frequencies,resonant gas micropump can provide the suitable pressure and mass flow to satisfy the requirements of micro refrigeration systems.