Model Of Ultrasonic Transducer Research Articles

An analytical model of ultrasonic transducers considering acoustic losses of contact surfaces

In this paper, a continuum electromechanical model of a Langevin ultrasonic transducer is developed considering acoustic losses of contact surfaces. The calculated energy losses between components of a transducer are considered as loss modulus of backing and matching parts. Considering the losses, the calculated vibrations amplitude of the transducer is matched to measured values. In addition, the calculated frequency response of the electrical admittance of the transducer is in good agreement with experimental results. The errors of calculated resonant frequency, anti-resonance frequency and amplitude of vibrations compared to the experimental results are 0.02%, 0.03%, 4.5% respectively. The values of the electrical admittance in the resonant and anti-resonant frequency have errors of 2.7%, 9.5% compared to empirical results. The developed model, fixes the drawback of previous models to anticipate amplitude of vibrations and the frequency response of the electrical admittance of ultrasonic transducers.

Design and Characterization of Ultrasonic Langevin Transducer 20 kHz Using a Stepped Horn Front-Mass

Ultrasonication is a method that is widely used in various fields. One of its applications is to accelerate the process of homogenization, emulsification, and extraction. In the ultrasonicator system, the transducer is an extremely important device. The resonant frequency, longitudinal vibration amplitude, and electromechanical coupling are the targets in designing an ultrasonic transducer. In this investigation, the main contribution was the development of a simple and effective method for mechanically tuning the resonant frequency of the transducer by adding mass to the front end of the mass or stepped horn. This study also aimed to obtain optimal results by examining the effects of geometric dimensions, bolt prestress, stress distribution, resonant frequency, amplitude, and electrical impedance. The ultrasonic transducer model was designed with a resonant frequency of 20 kHz and simulated using the finite element analysis. The steps involved included calculating the dimensions and geometric structure of the transducer, modeling using the finite-element method, and experimental validation. The simulation results and measurements showed that the series resonant frequency, electrical impedance, and effective electromechanical coupling of the Model-4 transducer 16∙13 mm radiator configuration were 20.15 kHz, 100 Ω, and 0.2229 from the simulation results, and 20.17 kHz, 24.91 Ω, and 0.2033 from the measurement results. A percentage difference, or relative error, of 0.1% was obtained between the simulation and the experimental results for this Model-4 with bolt prestressing at 15 kN.

Development of a contact layer in the finite element model of ultrasonic transducers to evaluate losses in contact surfaces

In this research, a 3D finite element model of an ultrasonic transducer has been developed, considering the losses between components. These losses are modeled by defining viscous dampers at interfaces. The friction between components is evaluated using the BKE contact mechanics model. The results show that the friction losses do not significantly reduce the vibration amplitude. However, due to the mismatch of acoustic impedances, the reflection of acoustic waves in the interfaces of components causes many power losses. By applying the equivalent damping, the error of the amplitude of the vibrations was reduced to 2.56%. In contrast, this error was very high in previous articles. The resonance and anti-resonance frequency errors are 2.63 and 0.86%, respectively.

Toward Ultrasonic Wire Bonding for High Power Device: A Vector Based Resonant Frequency Tracking and Constant Amplitude Control

The electrical packaging for high power devices such as IGBT or MOSFET is achieved by heavy aluminum ultrasonic wire bonding. In this process, the amplitude stability of ultrasonic transducer determines the bonding quality, which demands more accuracy in resonant frequency tracking (RFT) and constant amplitude control (CAC). In this investigation, we proposed a vector based resonant frequency (VRFT) tracking and vector based constant amplitude control (VCAC) to control the ultrasonic transducer. The current of dynamic branch was conducted by calculating the voltage and current vector of ultrasonic transducer. Small signal model of ultrasonic transducer was established and applied into RFT and CAC. A control strategy of fuzzy self-tuning PID closed loop was utilized to RFT and CAC. The PID parameters was calculated by the linear control theories and modified by the fuzzy controller which improved the vibration stability of the transducer. A prototype of 100Watt/60kHz ultrasonic driver was self-developed to verify the VRFT and VCAC. It demonstrated that the locked frequency of VRFT can be controlled within less than 0.04 millisecond when staring from the swept frequency, and the vibration response is fast with the varying bonding pressure. The amplitude of fuzzy PID VCAC is more stable and robust compared to the classical PID control, which improved the bonded joint quality in heavy aluminum wire packaging. Note to Practitioners—This article was motivated by the reliability and efficiency of IGBT/ MOSFET device packaging through ultrasonic aluminum wire bonding. This bonding process requires more amplitude stability of the ultrasonic transducer to achieve acceptable bonded quality. Currently, the resonant frequency tracking (RFT) by classical PID control is in slow speed, and the amplitude of the transducer cannot be controlled constantly due to the inherent static capacitor of the transducer. These issues for the ultrasonic control are originated from the engineer’s experience or simple heuristic rule instead of advanced approaches. To improve the vibration performance, we proposed a vector based model consisting of the relationship the dynamic branch current and the total current of the transducer, to control the RFT and constant amplitude control (CAC). Moreover, the vector based is utilized into the fuzzy PID control, where the calculation is reduced by area coefficient defuzzy. The verification experiments prove that the response time of the proposed vector based RFT and CAC, and the bonded joint quality is optimized obviously. It is noted that in our control strategy, the RMS value, the phase of voltage and current of the transducer are acquired by DSP processor, and the calculation of fuzzy PID controller is not complicated, which is feasible to implement in application. This significantly benefits the demand of accurate control to the ultrasonic power in electronic packaging.

Electromechanical Dynamics Model of Ultrasonic Transducer in Ultrasonic Machining Based on Equivalent Circuit Approach.

Ultrasonic transducer is a piezoelectric actuator that converts AC electrical energy into ultrasonic mechanical vibration to accelerate the material removal rate of workpiece in rotary ultrasonic machining (RUM). In this study, an impedance model of the ultrasonic transducer is established by the electromechanical equivalent approach. The impedance model not only facilitates the structure design of the ultrasonic transducer, but also predicts the effects of different mechanical structural dimensions on the impedance characteristics of the ultrasonic transducer. Moreover, the effects of extension length of the machining tool and the tightening torque of the clamping nut on the impedance characteristics of the ultrasonic transducer are investigated. Finally, through experimental analysis, the impedance transfer function with external force is established to analyze the dynamic characteristics of machining process.

Impedance Modeling of Ultrasonic Transducers Used in Heavy Aluminum Wire Bonding

Dynamic characteristics and ultrasonic properties of piezoelectric transducer determine the bonding quality in heavy aluminum wire bond packaging. In this paper, an impedance model for the ultrasonic transducers is developed by analytical calculations using the equivalent circuit method. This lumped model indicates the relationship between impedance and the other parameters such as material features, structure dimensions, loadings, driving electrical power, and material losses. This impedance model can be used not only for transducer design but also to predict the frequency and impedance at different loadings. The impedance model was numerically calculated using an analytical model and discussed with respect to three cases of loadings with and without a bonding tool and with a bonding tool in contact with the substrate. Four axial frequencies between 20 and 100 kHz were found for the ultrasonic transducer. The frequency and impedance of the transducer with the bonding tool were higher than those in the case without a bonding tool. When the bonding tool was in contact with the substrate, the resonance frequency decreased and the impedance increased. The experimental results obtained by frequency sweeping support the validity of the impedance model. The impedance model can be a benefit to transducer design and parameter match to electrical driver.

A Matlab/Simulink 3D model of unsymmetrical ultrasonic sandwich transducers

Ultrasonic sandwich transducer is a half-wave resonant structure which oscillates in thickness direction. This paper presents a new Matlab/ Simulink model of a prestressed unsymmetrical ultrasonic sandwich transducer, which is modeled by applying three-dimensional (3D) Matlab/Simulink models of piezoceramic rings and metal endings derived from the piezoceramic ring model. With the cascade connection of the piezoceramic rings model with metal endings model, a complete model of ultrasonic transducer is obtained. Using this model one may determine any transducer transfer function, whereat is taken into the account the external medium influence, as well as the influence of the thickness and radial modes of each transducer component. The electromechanical equivalent circuit of the hammer transducer, which represents onedimensional (1D) model, is also derived and presented in this paper. The comparisons between experimental and theoretical results are quite good and validate the new analytical 3D design approach.

Correlation of IVC Diameter and Collapsibility Index With Central Venous Pressure in the Assessment of Intravascular Volume in Critically Ill Patients.

ObjectiveThe objective of our study is to assess the correlation between inferior vena cava (IVC) diameters, central venous pressure (CVP) and the IVC collapsibility index for estimating the volume status in critically ill patients.MethodsThis cross-sectional study used the convenient sampling of 100 adult medical intensive care unit (ICU) patients for a period of three months. Patients ≥ 18 years of age with an intrathoracic central venous catheter terminating in the distal superior vena cava connected to the transducer to produce a CVP waveform were included in the study. A Mindray diagnostic ultrasound system model Z6 ultrasound machine (Mindray, NJ, USA) was used for all examinations. An Ultrasonic Transducer model 3C5P (Mindray, NJ, USA) for IVC imaging was utilized. A paired sampled t-test was used to compute the p-values.ResultsA total of 32/100 (32%) females and 68/100 (68%) males were included in the study with a mean age of 50.4 ± 19.3 years. The mean central venous pressure maintained was 10.38 ± 4.14 cmH2O with an inferior vena cava collapsibility index of 30.68 ± 10.93. There was a statistically significant relation among the mean CVP pressure, the IVC collapsibility index, the mean maximum and minimum IVC between groups as determined by one-way analysis of variance (ANOVA) (p < 0.001). There was a strong negative correlation between CVP and IVC collapsibility index (%), which was statistically significant (r = -0.827, n = 100, p < 0.0005). A strong positive correlation between CVP and maximum IVC diameter (r = 0.371, n = 100, p < 0.0005) and minimum IVC diameter (r = 0.572, n = 100, p < 0.0005) was found.ConclusionThere is a positive relationship of CVP with minimum and maximum IVC diameters but an inverse relationship with the IVC collapsibility index.

Hybrid Model of Ultrasonic Transducer for better Medical Imaging

Hybrid Model of Ultrasonic Transducer for better Medical Imaging

Component based modelling of piezoelectric ultrasonic actuators for machining applications

Ultrasonically Assisted Machining (UAM) is an emerging technology that has been utilized to improve the surface finishing in machining processes such as turning, milling, and drilling. In this context, piezoelectric ultrasonic transducers are being used to vibrate the cutting tip while machining at predetermined amplitude and frequency. However, modelling and simulation of these transducers is a tedious and difficult task. This is due to the inherent nonlinearities associated with smart materials. Therefore, this paper presents a component-based model of ultrasonic transducers that mimics the nonlinear behaviour of such a system. The system is decomposed into components, a mathematical model of each component is created, and the whole system model is accomplished by aggregating the basic components' model. System parameters are identified using Finite Element technique which then has been used to simulate the system in Matlab/SIMULINK. Various operation conditions are tested and performed to demonstrate the system performance.

Acoustic beam modeling of ultrasonic transducers and arrays using the impulse response and the discrete representation methods

The impulse response of the velocity potential and the discrete representation methods were used in order to model the acoustic field radiated by ultrasonic transducers and arrays. The first method deals with the calculation of the exact impulse response, in which solutions are possible only for simple geometries, such as the circular piston. The second method is an approximated solution based on the discretization of the acoustic aperture in small elementary areas, each of them radiating a spherical wave. By using circular transducers, which can be considered circular pistons, many simulations comparing the methods were carried out. The relation between the computational cost and the precision was analyzed, thus establishing the time and space discretization levels. The simulations were made using the Matlab software and the results were compared to experimental measurements showing good agreement. The experimental results were obtained using a scanning system. The acoustic field radiated from a 1 MHz circular transducer was measured as well as a 3.5 MHz array of 16 elements both immersed in water. The acoustic field radiated by the array was simulated and measured with focalization on a radius of 30 mm with deflections of 0º and 20º.

Modeling of circular piezoelectric micro ultrasonic transducer using CuAl10Ni5Fe4 on ZnO film for sonar applications

Modeling and theoretical characterization of piezoelectric micro ultrasonic transducer (pMUT) using ZnO film sandwiched between nickel aluminum bronze (CuAl10Ni5Fe4) electrodes was reported in this paper. The transducer is targeted to be utilized in sonar applications. Analyses on the model were carried out using finite element method. Model’s dimensional parameters were optimized for desired performance. Simplified technique was proposed to determine transmit and receive sensitivities of the model. As the result, micro ultrasonic transducer model with resonance frequency of 40 kHz was proposed with estimated receive and transmit sensitivities of −93 dB re 1 V/μPa and 137 dB re 1 μPa/V, respectively. Further model validations require actual device fabrication and this will be included in our future works.

Acoustical transmission line model for ultrasonic transducers for wide-bandwidth application

Abstract An improved model for ultrasonic transducers is proposed. By considering only the first symmetric mode, each layer is represented as an acoustical transmission line in modeling of bulk wave transducers. In imaging applications, wide bandwidth and short time duration are required. The approach we have used consists of impedance matching the front face of the piezoelectric transducer to the propagating medium with a quarter wavelength impedance matching layer and inserting an unmatching quarter wavelength acoustical layer between the rear face and backing material. A heavy backing would degrade the wide-band phenomena, but show a time duration shorter than 0.5 μs for imaging applications. PSPICE code of the controlled source model is implemented to precisely predict the performance of the matched transducers such as impedance, insertion loss, bandwidth and duration of the impulse response. Good agreement between the simulation and experimental results has been achieved.

Ultrasonic Piezoceramic Transducer Modeling With VHDL-AMS: Application to Ultrasound Nonlinear Parameter Simulations

This paper presents an ultrasonic transducer modeling with very high-speed integrated circuit (VHSIC) hardware description language-analog and mixed signal (VHDL-AMS) IEEE 1076.1 integrated in a global measurement cell modeling dedicated to biological tissue ultrasound characterization. Usual modeling of ultrasonic transducers is based on electrical analogy and is not simulated in the global measurement environment. The ultrasonic transducer modeling proposed is simulated with a nonlinear acoustic load and electronic excitation. The nonlinear B/A parameter is used to characterize a medium with a comparative method. The measurement cell is composed of two piezoelectric ceramic transducers, which are implemented with Redwood's electric scheme. The analyzed medium is placed between the transducers and modeled to take into account the nonlinear propagation with the B/A parameter. The usual transmission line model has been modified to take into account the nonlinear propagation for a one-dimensional (1-D) wave. Simulations of the transducer pulse response and electrical impedance show a VHDL-AMS model that is in good agreement with measurement and compared to the usual personal computer simulation program with integrated circuit emphasis results simulations. Results obtained by simulation of mediums (blood, milk, liver, and human fat tissue) showed good agreement between modeling and experimental measurement, and a maximum error of about 12.5% for B/A measurement-simulation

Predictions of the effect of some constructional variables on the performance of ultrasonic transducers

A recently published model of ultrasonic transducers is used, together with one-dimensional description of ultrasonic propagation, to predict their electrical and ultrasonic properties. Particular attention is paid to the effect that constructional variations may have on the performance of the assembled transducer construction, but more specific calculations would be necessary to determine these limits for particular probe designs.