A flextensional transducer with an Omega shape and its algorithmic method of the resonant frequency and the shape functions are suggested. The Omega transducer is separated into four parts treated respectively as a th...A flextensional transducer with an Omega shape and its algorithmic method of the resonant frequency and the shape functions are suggested. The Omega transducer is separated into four parts treated respectively as a thin shell of revolution and the theories of thin shells of revolution and piezoelectricity are used to obtain the energy functional of each part so that the sum of the energy functionals of the four parts is the energy functional of the whole Omega transducer. By substituting the shape functions with undetermined coefi3cients and the geo- metrical boundary conditions into the energy functional of the Omega transducer, the resonant frequency of the Omega transducer is firstly determined with the Rayleigh-Ritz method. With the gotten resonant frequency, the constant coefficients of the shape functions are following solved through the Rayleigh-Ritz partial differential equations and the geometrical boundary condition equations. The solving method of the resonant frequency and the shape functions is also extended to the cymbal transducer. Such an analytical method is verified to be feasible by the results of the finite element analysis and experiments. The research indicates that （1） The radial vibration of the piezoelectric ceramic is in phase with the longitudinal vibration of the top of metal cap, and it cut down the reversed phase component in the sound field. The Omega transducer can be a low frequency transducer. （2） The determination method of the resonant frequency and the shape functions give a solution to the optimum designs of the Omega transducer and the cymbal transducer. （3） The determination method of the resonant fi＇equency and the shape functions can also be used in other flextensional transducers or other structures which are composed of thin shells of revolution, so it is universal.展开更多
With the required increased audio pressure of the parametric ultrasonic transducer array and the difficulty to theoretically analyse the complex ultrasonic structure in audio beam application, an computationally effic...With the required increased audio pressure of the parametric ultrasonic transducer array and the difficulty to theoretically analyse the complex ultrasonic structure in audio beam application, an computationally efficient model is desired to describe the characteristic of the parametric ultrasonic transducer array for the system design and optimization. By applying the symmetry boundary conditions at the mid-plane in the thickness direction, a finite element model based on the haft thickness simplification is presented to analyze the parametric circular transducer which is designed by gluing the poly Vinylidene fluoride film （PVDF）. The validity of the proposed model is confn＇med by a comparison of finite element analysis results with the theoretical value and experimental data, which show that they are making a good agreement with each other.展开更多
Capacitive micromechanical ultrasonic transducers(CMUTs)have been widely studied because they can be used as substitutes for piezoelectric ultrasonic transducers in imaging applications.However,it is unclear whether a...Capacitive micromechanical ultrasonic transducers(CMUTs)have been widely studied because they can be used as substitutes for piezoelectric ultrasonic transducers in imaging applications.However,it is unclear whether and how CMUTs can be developed for sensors incorporating other functions.For instance,researchers have proposed the use of CMUTs for pressure sensing,but fundamental and practical application issues remain unsolved.This study explored ways in which a pressure sensor can be properly developed based on a CMUT prototype using a simulation approach.A three-dimensional finite element model of CMUTs was designed using the COMSOL Multiphysics software by combining the working principle of CMUTs with pressure sensing characteristics in which the resonance frequency of the CMUT cell shifts accordingly when it is subjected to an external pressure.Simultaneously,when subjected to pressure,the CMUT membrane deforms,thus the pressure can be reflected by the change in the capacitance.展开更多
基金supported by the Young Scientists Ftmd of the National Natural Science Foundation of China(51005241)the Postdoctoral Science and Technology Activities Preferred Financing Project in Hubei Province
文摘A flextensional transducer with an Omega shape and its algorithmic method of the resonant frequency and the shape functions are suggested. The Omega transducer is separated into four parts treated respectively as a thin shell of revolution and the theories of thin shells of revolution and piezoelectricity are used to obtain the energy functional of each part so that the sum of the energy functionals of the four parts is the energy functional of the whole Omega transducer. By substituting the shape functions with undetermined coefi3cients and the geo- metrical boundary conditions into the energy functional of the Omega transducer, the resonant frequency of the Omega transducer is firstly determined with the Rayleigh-Ritz method. With the gotten resonant frequency, the constant coefficients of the shape functions are following solved through the Rayleigh-Ritz partial differential equations and the geometrical boundary condition equations. The solving method of the resonant frequency and the shape functions is also extended to the cymbal transducer. Such an analytical method is verified to be feasible by the results of the finite element analysis and experiments. The research indicates that （1） The radial vibration of the piezoelectric ceramic is in phase with the longitudinal vibration of the top of metal cap, and it cut down the reversed phase component in the sound field. The Omega transducer can be a low frequency transducer. （2） The determination method of the resonant frequency and the shape functions give a solution to the optimum designs of the Omega transducer and the cymbal transducer. （3） The determination method of the resonant fi＇equency and the shape functions can also be used in other flextensional transducers or other structures which are composed of thin shells of revolution, so it is universal.
基金Supported by the National Natural Science Foundation of China (No. 60302001)
文摘With the required increased audio pressure of the parametric ultrasonic transducer array and the difficulty to theoretically analyse the complex ultrasonic structure in audio beam application, an computationally efficient model is desired to describe the characteristic of the parametric ultrasonic transducer array for the system design and optimization. By applying the symmetry boundary conditions at the mid-plane in the thickness direction, a finite element model based on the haft thickness simplification is presented to analyze the parametric circular transducer which is designed by gluing the poly Vinylidene fluoride film （PVDF）. The validity of the proposed model is confn＇med by a comparison of finite element analysis results with the theoretical value and experimental data, which show that they are making a good agreement with each other.
文摘Capacitive micromechanical ultrasonic transducers(CMUTs)have been widely studied because they can be used as substitutes for piezoelectric ultrasonic transducers in imaging applications.However,it is unclear whether and how CMUTs can be developed for sensors incorporating other functions.For instance,researchers have proposed the use of CMUTs for pressure sensing,but fundamental and practical application issues remain unsolved.This study explored ways in which a pressure sensor can be properly developed based on a CMUT prototype using a simulation approach.A three-dimensional finite element model of CMUTs was designed using the COMSOL Multiphysics software by combining the working principle of CMUTs with pressure sensing characteristics in which the resonance frequency of the CMUT cell shifts accordingly when it is subjected to an external pressure.Simultaneously,when subjected to pressure,the CMUT membrane deforms,thus the pressure can be reflected by the change in the capacitance.
