Sandwich Piezoelectric Transducer Research Articles

Design of a Compact 3-D Vibration-Assisted Turning Device With Large Amplitude and High Frequency for Diversified Microstructure Sculpturing

The 3D vibration-assisted turning (VAT) has attracted increasing attention for its merits in microstructure sculpturing and ultra-precision machining. However, most current 3D VAT tools adopt complex structures and it is still difficult to implement high frequency and large amplitude simultaneously on a simple integrated tool. Here, a 3D VAT tool with high-frequency and large amplitude adjustment capability is proposed for the first time, which adopts a more stable and compact single sandwich piezoelectric transducer structure. High frequency and large amplitude adjustment capabilities improve the machining efficiency and the range of machinable microstructures. The structure of the tool is simplified by using the sandwich-type single transducer structure, which is convenient to reduce cost and improve machining stability. Surface microstructures with variable inclination angles and distribution ratios are firstly sculptured by the proposed 3D VAT tool, which provides a new idea for surface modification. In addition, surface microstructures with different depths and high-precision microgrooves are machined, and better machining results are obtained. The texture depth and machining efficiency of microstructure are increased with the increase of amplitude and frequency. Microgrooves with a surface roughness of Sa 29 nm, minimized burrs and defects, and a specific cutting force reduction of 54.8% are obtained.

Design, modeling and experimental research of a multi-mode, fast-response piezoelectric control valve

To realize the precise regulation and fast response of the valve, a piezoelectric control valve with a simple and compact structure, and easy control is proposed. The control valve is divided into the valve core that consists of a sandwich piezoelectric transducer and a valve body. When a single excitation signal is applied to the transducer, the longitudinal vibration mode of the valve core is excited. The valve is opened due to the liner reciprocating motion of the end of the valve core. By adjusting the frequency of the excitation signal, the vibration mode of the transducer is switched between the first three modes of longitudinal vibration, which in turn adjusts the water output of the valve. Compared with the single-mode valve, the piezoelectric control valve has three working modes. Therefore, it has different adjustment precision and range for each mode. First, the electromechanical coupling model of the valve core and the mechanical model of the valve body are established by using the transfer matrix method. By analyzing the dynamic characteristics of the piezoelectric valve, the structure parameters of the valve core and valve body are optimized. Secondly, the prototype of piezoelectric valve is manufactured and assembled, and the validity of the proposed theoretical model is verified by the vibration measurement experiments. Finally, the flow performance and response speed of the piezoelectric valve are measured by experiments. The results show that the maximum pressure of the valve is 1 MPa when the assembly pre-pressure is 983 N. A sinusoidal-signal has the best excitation effect. Under the experimental conditions of sinusoidal excitation, a driving voltage amplitude of 250 V, and pressure of 1 MPa, the optimal driving frequencies of the piezoelectric valve in the first three operating modes are 33.8 kHz, 42.2 kHz, and 83 kHz, and the corresponding maximum flow rates are 3.3 mL/min, 1.15 ml/min, and 0.445 ml/min, respectively. The response performance of the piezoelectric valve is tested, indicating that the prototype can achieve stable operation within 3.5 ms after being powered on, and stop working within 5 ms after being powered off. The piezoelectric valve has good response characteristics and flow control ability, which has potential applications in the field of biomedicine.

Research on vibration characteristics of the longitudinal-radial composite piezoelectric ultrasonic transducer

The transducer with high power capacity and extensive radiating area is required in some industrial processes like ultrasonic sonochemistry, ultrasonic cleaning and ultrasonic defoaming and so on. In order to achieve the desired effects, the longitudinal-radial composite piezoelectric ultrasonic transducer is proposed in this paper. The transducer is composed of a longitudinal sandwich piezoelectric transducer, a stepped ultrasonic horn and a metal sphere. The longitudinal vibrations of the sandwich piezoelectric transducer and the stepped ultrasonic horn excite the radial vibration of the metal sphere so that the longitudinal-radial coupled vibration of the transducer is achieved. The equivalent circuits for a sphere in radial vibration and for the entire system in longitudinal-radial coupled vibration have been developed. To validate the proposed equivalent circuits, the vibration characteristics of the transducer are investigated using the equivalent circuit method, numerical method, and experiment. The resonance frequencies obtained from the equivalent circuit method, numerical method and experiment are 29992 Hz, 29990 Hz and 30590 Hz, respectively, and the simulated and experimental results indicate that the frequencies correspond to the designed longitudinal-radial coupled resonance mode of the transducer. The measured frequency and displacement distribution showed good agreement with the analytical and numerical calculation results.

Design and optimization of a half-wavelength ultrasonic bone scalpel

Compared with traditional orthopedic surgical instruments, the ultrasonic bone scalpel (UBS) has obvious advantages in both safety and effectiveness. Based on the structure of the sandwich piezoelectric transducer, a design of half-wavelength UBS with a longitudinal vibration frequency of 22.5 kHz is proposed in this study. Firstly, the dimensions of each component of the UBS are calculated by the transmission matrix method, the initial design is verified by modal analysis, and the error is optimized by the response surface method. Then the harmonic response analysis is used to calculate the UBS’s tip amplitude, impedance and stress distribution. In addition, the influence of bolt pre-tightening force on the vibration characteristics of the UBS is analyzed. When the bolt pre-tightening force is 50-90MPa, the vibration performance of the UBS is stable, and the tip amplitude is large, which provides a reference for selecting appropriate tightening torque when the UBS is assembled. Finally, the bone-cutting experiment shows that the UBS has good cutting performance.

Generation of the small tin-droplet streams with a manipulable droplet spacing via the forced velocity perturbation

In extreme ultraviolet (EUV) sources, small tin droplets are scattered into the tin mist/disk under the irradiation of the pulsed laser to produce the EUV light. Small droplet size and large droplet spacing are required to suppress debris production to protect expensive collector mirrors. To this end, a tin-droplet generator with a capillary glass nozzle was designed and built to produce uniform tin-droplet streams with the droplet diameter less than 50 μm. Meanwhile, a forced perturbation, generated by a sandwich piezoelectric transducer, was loaded into a liquid tin jet to manipulate the droplet spacing through a stepped rod. The mono-sized tin-droplet streams with an average diameter of 42 μm were successfully produced in both the Rayleigh and the forced jet breakup regimes. A two-dimensional (2D) axisymmetric model was proposed to reveal the influence of the velocity perturbation amplitude on jet breakup patterns at different wavelengths. An F*–λ* (The dimensionless perturbation velocity amplitude F*–The dimensionless wavenumber l*) map was built, and five different droplet breakup patterns were identified based on simulations. Numerical simulations indicated that the droplet spacing could be increased by providing extra momentum to droplets from the forced velocity perturbation. Finally, by increasing the velocity perturbation amplitude, the droplet spacing was increased from ∼9Dd (droplet diameter) to ∼19Dd without significantly increasing the droplet size. This work provides a novel approach to obtaining small mono-sized tin-droplet streams with manipulable droplet spacing.

Research on Inherent Frequency and Vibration Characteristics of Sandwich Piezoelectric Ceramic Transducer

Great progress has been made in the field of ultrasonic processing in recent years, and piezoelectric ceramic transducers have been widely used as drive sources. In this paper, a sandwich piezoelectric ceramic transducer is designed, and the vibration of each part of the transducer is analyzed by elastic mechanics and piezoelectric theory. According to its mechanical and electrical boundary conditions, the vibration model of the piezoelectric transducer was established. Based on the equivalent elastic modulus method for simplifying the pre-stressed bolts into a one-dimensional transducer vibration model, the relationship between the one-dimensional axial response frequency of the transducer and the length of each component was obtained. Based on the half wavelength theory, a transducer with the vibration node in the crystal stack and an inherent frequency of 15 kHz was designed and fabricated. In order to verify the natural frequency and vibration characteristics of the piezoelectric transducer, a laser vibration measurement system was built in this study. The vibration characteristics of the transducer under different parameters such as voltage and frequency were analyzed, and the accuracy of the vibration model was verified. The vibration states of the end surface of the transducer and the radial surface were evaluated at the first-order inherent frequency and second-order inherent frequency. The results show that the equivalent simplified model established in this study can effectively design the inherent frequency of the transducer, and the operation at the first-order inherent frequency meets the one-dimensional assumptions of this study. The transducer operating conditions measured in this study also provide a more detailed reference for ultrasonic processing applications.

Design of Hollow Horn Based on Four-terminal Network Method

When designing the horn of the ultrasonic transducer for rotary machining, the traditional analytical method cannot consider the complex assembly cross-section of the horn, resulting in a large final simulation error and design error. At the same time, when the design diameter of the transducer is too large, the size of the back mass obtained by the traditional analytical method is too thin. This paper combines the four terminal network method and the finite element method, selects the sandwich piezoelectric transducer, takes the ER spring chuck commonly used in rotary machining as an example, derives the transmission matrix corresponding to the geometric cross-section shape, and then uses the four-terminal network method and the traditional analytical method to design two sets of stepped ultrasonic transducers with the design frequency of 22 kHz for analysis and comparison. Finally, through the analysis, it is verified that the ultrasonic transducer designed by the four-terminal network method has a performance closer to the theoretical design.

Nonlinear Equivalent Circuit of High-Power Sandwich Piezoelectric Ultrasonic Transducer.

In the theoretical design and analysis of the sandwich piezoelectric ultrasonic transducer, the transducer is considered to be an ideal linear system, where the dielectric, piezoelectric, and mechanical losses are neglected. However, when the transducer is driven at high power, the losses are becoming several times higher comparing them to low signal measurements, and the transducer works in a nonlinear state. In order to predict the performance of the transducer at high power, the nonlinear parameters (complex constants) of the piezoelectric materials are introduced. The corresponding nonlinear equivalent longitudinal wave sound velocity and the nonlinear equivalent longitudinal wavenumber of the piezoelectric ceramics are derived. Then, the nonlinear equivalent circuit (NEC) and the nonlinear resonance frequency equation of the high-power sandwich piezoelectric ultrasonic transducer that related with the losses are deduced. Then, the nonlinear finite element model (NFEM) of the transducer is constructed. The performance parameters of the transducer obtained by the NEC method and the finite element (FE) method are compared with each other, and consistent results have been achieved by two methods. Finally, the contribution of various losses is obtained through theoretical calculation, simulation, and experimental measurement, and the correctness of the theoretical model in this article is verified.

WITHDRAWN: Design of a probe-type acoustic tweezer by acoustic-streaming field optimization

• The evaluation criteria of acoustic-streaming field optimization are proposed. • The optimized capture condition is concluded by finite element analysis. • Ultrasonic vibration device for optimized capture vibration parameter is designed. • The probe-type acoustic tweezer can capture, translate and release objects. This paper presents a novel design process of a probe-type acoustic tweezer for micro/nano manipulation. The qualitative evaluation criteria of manipulation-oriented acoustic-streaming field are proposed, and the optimized capture condition is concluded by finite element optimization accordingly for the first time. The scheme of ultrasonic vibration device for optimized capture condition is proposed, which is composed of two parallel-connected sandwich piezoelectric transducers. Initial structural parameters of the vibration device are determined by an analytical model based on the electromechanical equivalent theory, and it is further optimized using finite element method. Dynamic performances of the vibration device are then analyzed through modal analysis and frequency response analysis. A prototyped vibration device is fabricated and experimental investigations are conducted to further test its characteristics. The results show that the device can vibrate with the optimized capture condition. The experimental setup of the probe-type acoustic tweezer system is established, and it is proven that it can successfully capture, translate and release nanowires. Graphical Abstract. .

The High-Power Piezoelectric Transformer With Multiple Outputs Based on Sandwiched Piezoelectric Transducers

This article develops a high-power piezoelectric transformer based on the sandwiched piezoelectric transducer with multioutput characteristics. An advanced high-power voltage transformation technology is realized via using the superior mechanical robustness of the sandwiched piezoelectric transducers. High-power sandwiched piezoelectric transformers (s-PTs) with the unique crisscrossed structure are constructed by four sandwiched piezoelectric transducers with two modes, i.e., antiphase mode and in-phase mode, due to the coupled vibration of the central metal cuboid. Moreover, the related electromechanical equivalent circuit model (EECM) of the s-PTs is established in which two loss factors are introduced into this model, and its impedance characteristics, voltage gains, and power gains are studied as well. The accuracy of EECM is verified by the finite element method and experiments. Results reveal that s-PT has three outputs, and its voltage gains and power ratios are affected by load resistance and loss. The output power of the s-PTs can reach at least 45 W, and the s-PTs can keep the efficiency of ∼35% under high-input electric power, which provides a new idea for high-power piezoelectric transformers.

A Y-Type Sandwich Piezoelectric Transducer in Longitudinal-Longitudinal Coupled Vibration Excited by Two Groups of Piezoelectric Ceramic Stack

A Y-Type Sandwich Piezoelectric Transducer in Longitudinal-Longitudinal Coupled Vibration Excited by Two Groups of Piezoelectric Ceramic Stack

Theoretical modeling, verification, and application study on a novel bending-bending coupled piezoelectric ultrasonic transducer

Commercialized ultrasonic algae removal systems generally adopt multiple Langevin ultrasonic transducers to produce omnidirectional ultrasound radiation, leading to complex configuration and control systems, low efficiency, high energy consumption, and high cost. In order to ease these issues, a novel bending-bending coupled piezoelectric ultrasonic transducer is proposed, theoretically modeled, and experimentally investigated in this study. Two groups of piezoelectric ceramics with dual polarization zones are sandwiched between two metal blocks, which are used to produce two orthogonal and identical bending vibration modes. With the coupling of the two bending vibration modes, the proposed sandwich piezoelectric transducer can produce omnidirectional ultrasonic irradiation for algae removal, which can greatly simplify the configuration and control system of ultrasonic algae removal system, lower energy consumption, and improve removal efficiency. A novel transfer matrix model of describing the bending-bending coupled vibration is first created for the combined piezoelectric element with dual polarization zones by simultaneously considering its electrical and mechanical properties. Then an electromechanical coupling model of the proposed transducer is developed to reveal its dynamic behavior. In addition, the vibration characteristics of the transducer prototype are tested, in order to verify the feasibility of the transducer design and operating principle and to confirm the correctness of the developed electromechanical coupling model. Finally, an application study is carried out to evaluate the algae removal effect of the proposed transducer prototype. At ultrasonic intensities of 0.014 W/mL and 0.021 W/mL, the algal removal rate, respectively, reached 45.83% and 63.27% when the ultrasonic irradiation time was 60 min, presenting efficient algae removal effect. Compared to the traditional Langevin ultrasonic transducers, the proposed transducer can achieve omni-directional ultrasonic radiation, greatly simplifying the structure and drive circuit of the ultrasonic algae removing system. It has a good application prospect in the field of environmental protection and water purification.

Novel Traveling Wave Sandwich Piezoelectric Transducer with Single Phase Drive: Theoretical Modeling, Experimental Validation, and Application Investigation

Most of traditional traveling wave piezoelectric transducers are driven by two phase different excitation signals, leading to a complex control system and seriously limiting their applications in industry. To overcome these issues, a novel traveling wave sandwich piezoelectric transducer with a single-phase drive is proposed in this study. Traveling waves are produced in two driving rings of the transducer while the longitudinal vibration is excited in its sandwich composite beam, due to the coupling property of the combined structure. This results in the production of elliptical motions in the two driving rings to achieve the drive function. An analytical model is firstly developed using the transfer matrix method to analyze the dynamic behavior of the proposed transducer. Its vibration characteristics are measured and compared with computational results to validate the effectiveness of the proposed analytical model. Besides, the driving concept of the transducer is investigated by computing the motion trajectory of surface points of the driving ring and the quality of traveling wave of the driving ring. Additionally, application example investigations on the driving effect of the proposed transducer are carried out by constructing and assembling a tracked mobile system. Experimental results indicated that 1) the assembled tracked mobile system moved in the driving frequency of 19410 Hz corresponding to its maximum mean velocity through frequency sensitivity experiments; 2) motion characteristic and traction performance measurements of the system prototype presented its maximum mean velocity with 59 mm/s and its maximum stalling traction force with 1.65 N, at the excitation voltage of 500 VRMS. These experimental results demonstrate the feasibility of the proposed traveling wave sandwich piezoelectric transducer.

Vibration characteristics of two-dimensional orthogonalcomposite sandwich piezoelectric circular transducer

Vibration characteristics of two-dimensional orthogonalcomposite sandwich piezoelectric circular transducer

Large-dimension piezoelectric ceramic composite transducer with point-defect, square-lattice phononic crystal

<p indent=0mm>To improve the longitudinal working efficiency of large-dimension sandwich piezoelectric ceramic composite transducers (PccTs), reduce the strong coupling between longitudinal and transverse vibrations, and improve the longitudinal displacement distribution uniformity of the front radiation end of the transducer, three rows and three columns of two-dimensional (2D) air cylindrical holes arranged in a square lattice parallel to the axial direction of the transducer were fabricated on the front cover plate of a large-dimension sandwich PccT. By changing the radius of the air cylindrical hole in the center of the 3×3 supercell, a point defect is introduced to construct 2D square lattice near-periodic phononic crystals based on the abnormal radius point defect. This design can use the incomplete bandgap of the crystal in the radial direction to suppress the transverse vibration of the large-dimension PccT and can use the Anderson localization characteristics of the point defect to adjust the intensity and phase of the local sound field to further improve the uniformity of the displacement distribution of the radiation surface of the front cover plate. In addition, the influence of the structural parameters of the air cylindrical hole with the point defect on the longitudinal resonance frequency and the longitudinal vibration displacement distribution is analyzed. The simulation results show that the large-dimension PccT based on point defect, phononic crystals can suppress the axial stray modal of the transducer, significantly optimize the longitudinal relative displacement distribution of the radiation surface, and improve the performance of large-dimension PccTs.

Analysis on coupled vibration of piezoelectric ceramic stack with two piezoelectric ceramic elements.

A longitudinally polarized piezoelectric ceramic stack with two piezoelectric ceramic elements is an important part of sandwich piezoelectric transducers. The three-dimensional coupled vibration of piezoelectric ceramic stack is analyzed. Since the longitudinal and radial dimensions of particular piezoelectric ceramic stacks are approximately equal, one-dimensional theory cannot be used for analysis. The piezoelectric ceramic stack is analyzed by the equivalent elastic method, which is an approximate analytical method, and it is considered that the coupled vibration of a piezoelectric ceramic stack is composed of equivalent radial and longitudinal vibrations. These two equivalent vibrations are connected by a mechanical coupling coefficient. The radial and longitudinal electromechanical equivalent circuits are obtained, and the resonance frequency equations are derived. The dependency of the radial and longitudinal resonance frequencies on the geometrical dimensions for piezoelectric ceramic stack is analyzed. The height or radius has a large influence on the longitudinal resonance frequency or the radial resonance frequency. Two sets of piezoelectric ceramic stacks are fabricated. The experimental results, COMSOL simulated results, and theoretical results are in good agreement.

Semi-analytical modeling and optimization of a traveling wave sandwich piezoelectric transducer with a beam-ring combined structure

Abstract Boasting the advantages of low maximum ground pressure and low locomotion resistance of tracked mechanisms, a traveling wave sandwich piezoelectric transducer with a beam-ring combined structure was proposed and developed to directly drive a metal track, and preliminary experimental investigations have confirmed the feasibility of the transducer design and its operating principle. However, the dynamic behavior of the sandwich piezoelectric transducer has not yet been studied theoretically. To enable practical applications, the sandwich piezoelectric transducer needs to be optimized for better output performances. Therefore, a semi-analytical model is of significance to describe the dynamic behavior of the sandwich piezoelectric transducer, to predict its driving effect, and to improve its output performance. In this study, an electromechanical coupling model is developed for the sandwich piezoelectric transducer by employing the transfer matrix method, in which a novel longitudinal-bending coupling vibration transfer matrix is created for the combined PZT elements and an in-plane bending vibration transfer matrix is developed for the closed curved beam element. To validate the proposed model, experimental investigations are carried out to measure the dynamic behavior of the transducer prototype and compare to calculation results. The differences between the measured and calculated resonant frequencies for two operating vibration modes are, respectively, 74 Hz and 63 Hz. Also the vibration shapes at the respective resonant frequencies match well. Comparisons demonstrate the feasibility of the developed transfer matrix model. To improve the output performance of the transducer, model-based optimization is conducted. The optimized geometrical sizes are obtained to meet optimization goals of the transducer.

A novel additive manufactured three-dimensional piezoelectric transducer: Systematic modeling and experimental validation

Abstract Sandwich piezoelectric transducers are widely used in many industrial applications due to their attractive advantages of compact structure, no electromagnetic interference, and excellent output performance. V-shaped piezoelectric transducers, a typical design, have been adopted as the stator of ultrasonic motors and the machining tool of elliptical vibration surface manufacturing. However, traditional V-shaped piezoelectric transducers were designed with one contact interface to output effective vibration, limiting their applications. To achieve multi contact areas with synchronous actuation function, a novel three-dimensional sandwich piezoelectric transducer is proposed in this study, expecting to drive wheels of a robotic mobile system. Two orthogonal Langevin transducers are adopted to vertically couple in a cylinder, producing two bending vibrations with a spatial phase difference of π/2 in the cylinder. Therefore, elliptical motion is generated at surface points of two driving parts placed at both ends of the cylinder. Due to the fact that two front-end blocks of the two Langevin transducers and the cylinder form a three-dimensional configuration which hard to be manufactured by traditional machining methods, this part is printed using laser additive manufacturing. To analyze the dynamic behavior of the proposed three-dimensional transducer, an analytical model is carried out utilizing the transfer matrix method for providing systematic modeling. This developed transfer matrix model is not only capable of greatly reducing computation efforts, and it is maybe suitable for the analysis of traditional V-shaped transducers. To validate this developed transfer matrix model and confirm the feasibility of the transducer design, experimental investigations are conducted to measure the vibration characteristics of the proposed transducer prototype using a 3D laser Doppler vibrometer and are compared to the calculation results. The measured and computed resonant frequencies of the transducer are 19.975 kHz and 20.045 kHz for the symmetrical vibration mode, and 20.07 kHz and 20.06 kHz for the anti-symmetrical vibration mode, respectively. Comparisons show that calculation results match well with the experimental results, demonstrating the effectiveness of the developed transfer matrix model and the feasibility of the three-dimensional transducer design.

Design and finite element simulation of an ultrasonic transducer of two piezoelectric discs

With the developing of ultrasound technology and expending of it’s application scope, new requirements for the structure and the energy radiation of the transducer are presented. A reasonable design and manufacture of the transducer ensures that the energy can be transmitted with minimal loss. Based on the longitudinal vibration equation, a sandwich piezoelectric transducer which can be used in the field of precision machining, medical and other fields is designed and simulated in this paper. Different from the ordinary transducer, the front cover of this transducer is also a horn which can amplify the output amplitude compared to an equal section circular bar. ANSYS15.0 is used to calculate and analyze the transducer model with using HyperMesh (HM) software to generate the mesh to ensure the quality of the mesh. The finite element analysis software can calculate the transducer modal and harmonic response, and the results can be used to compare with theoretical design. The design frequency of the transducer is 20 kHz, the error between the simulation and the theoretical value is less than five percent, the result obtained by ANSYS is very close to the theoretical design.

The Effect of Electrical Impedance Matching on the Electromechanical Characteristics of Sandwiched Piezoelectric Ultrasonic Transducers.

For achieving the power maximum transmission, the electrical impedance matching (EIM) for piezoelectric ultrasonic transducers is highly required. In this paper, the effect of EIM networks on the electromechanical characteristics of sandwiched piezoelectric ultrasonic transducers is investigated in time and frequency domains, based on the PSpice model of single sandwiched piezoelectric ultrasonic transducer. The above-mentioned EIM networks include, series capacitance and parallel inductance (I type) and series inductance and parallel capacitance (II type). It is shown that when I and II type EIM networks are used, the resonance and anti-resonance frequencies and the received signal tailing are decreased; II type makes the electro-acoustic power ratio and the signal tailing smaller whereas it makes the electro-acoustic gain ratio larger at resonance frequency. In addition, I type makes the effective electromechanical coupling coefficient increase and II type makes it decrease; II type make the power spectral density at resonance frequency more dramatically increased. Specially, the electro-acoustic power ratio has maximum value near anti-resonance frequency, while the electro-acoustic gain ratio has maximum value near resonance frequency. It can be found that the theoretically analyzed results have good consistency with the measured ones.