Model Of Transducer Research Articles

Investigation of a piezoelectric ultrasonic surface wave transducer that minimizes structural scattering

Abstract The Structural of ultrasonic surface wave transducers affects structural scattering. A numerical model of an ultrasonic surface wave transducer was established. Numerical simulations and dynamic acoustic analysis were performed to systematically assess, the effects of the transducer parameters, such as the front and back angles, matching layer, and front wedge shape on structural scattering. The results show that the acoustic amplitude of the transducer structure scattered waves is basically stable when the back angle of the wedge is 64° -68 °and the front angle is 65°-85°. The amplitude obtained from a transducer with orthogonal slots and a front uniform matching layer is 61% lower for the primary structure scattering, 56% lower for the secondary structure scattering.
When equipped with the upper matching layer, the amplitude of the secondary structural scattering echo is reduced by 78.2%. The experimental results show that the transducer with orthogonal slots on the wedge and a matching layer at the front and upper edges has a signal-to-noise ratio of 19.6dB when detecting the echo signal of a ϕ8 through-hole in a welded steel plate, indicating good detection capability. The experiment validates the numerical simulation results. The proposed transducer can be used for structural monitoring of welded structures and detecting flaws.

Modeling and Simulation of 2D Transducers Based on Suspended Graphene-Based Heterostructures in Nanoelectromechanical Pressure Sensors.

Graphene-based two-dimensional (2D) heterostructures exhibit excellent mechanical and electrical properties, which are expected to exhibit better performances than graphene for nanoelectromechanical pressure sensors. Here, we built pressure sensor models based on suspended heterostructures of graphene/h-BN, graphene/MoS2, and graphene/MoSe2 by using COMSOL Multiphysics finite element software. We found that suspended circular 2D membranes show the best sensitivity to pressures compared to rectangular and square ones. We simulated the deflections, strains, resonant frequencies, and Young's moduli of suspended graphene-based heterostructures under the conditions of different applied pressures and geometrical sizes, built-in tensions, and the number of atomic layers of 2D membranes. The Young's moduli of 2D heterostructures of graphene, graphene/h-BN, graphene/MoS2, and graphene/MoSe2 were estimated to be 1.001 TPa, 921.08, 551.11, and 475.68 GPa, respectively. We also discuss the effect of highly asymmetric cavities on device performance. These results would contribute to the understanding of the mechanical properties of graphene-based heterostructures and would be helpful for the design and manufacture of high-performance NEMS pressure sensors.

Design and Modeling of Coreless Magnetoelectric Transducers for Snake-like Wave Energy Converters

With the development of the economy, people’s demand for energy is increasing, which has led to a shortage of fossil fuels. Wave energy is a widely distributed renewable energy source, and the development of wave energy generation technology can greatly alleviate the energy shortage problem. This study takes the snake-like wave energy converter (WEC) as an example and designs a coreless magnetoelectric transducer for it. The structure of the coreless magnetoelectric transducer is relatively simple, eliminating the iron core in the transducer, which can eliminate its own damping. At the same time, this structure can minimize the gap between the magnet and the coil, improve energy conversion efficiency, and work continuously under complex working conditions. This study takes two types of coreless magnetoelectric transducers as examples to analyze. This study aims to establish equivalent magnetic circuit models for the coreless magnetoelectric transducers, explore the effects of different magnets on the performance of the transducers, and optimize the parameters in the transducers. We used simulation software to analyze the transducer and verify the accuracy of the models. Finally, prototypes of the coreless magnetoelectric transducers were made, and a testing system for the transducer was established to test its energy conversion capability. Our experiments show that coreless magnetoelectric transducers have good energy conversion capabilities and can be used as transducers for snake-like WECs. At the same time, this type of transducer can also be applied to other types of WECs, providing a new approach for the research of WECs.

A New 3-D Model of Composite Ultrasonic Transducer

A New 3-D Model of Composite Ultrasonic Transducer

Finite Element Method Modelling for Extended Depth of Focus Acoustic Transducer

Abstract Extended depth of focus (DOF) with the high lateral resolution is the primary requirement of the transducer in scanning acoustic microscopy to generate high-resolution images of the 3-dimensional sample over a large depth. Traditionally, focused ultrasonic spherical transducers are used to tightly focus the acoustic waves generated from a piezoelectric material for a wide range of applications in industrial, medical, and other fields. Such transducers have a problem of narrow DOF which restricts the imaging range in depth. In the present work, we propose three different transducer designs such as single axicon, central flat axicon and double axicon, which enable the possibilities of high transverse resolution imaging over greater depths due to the significant increase in DOF. Finite element modeling (FEM) in COMSOL of a spherical, single axicon, central flat axicon, and double axicon transducer is systematically performed and compared in terms of transverse resolution, DOF, and acoustic pressure in the central lobe. In addition, the single axicon and double axicon transducer modeling are done for different apex angles. It is observed that the central flat axicon transducer allows customizable DOF and the double axicon transducer provides high lateral resolution and reduced pressure in the side lobes compared to a single axicon lens.

A distributed parameter model of the cavity-loaded piston transducer

Abstract Adding a cylindrical liquid cavity at the radiation surface of a piston transducer can introduce the liquid cavity resonance into the vibration system, thereby extending the operating bandwidth of the transducer. However, recent studies have shown that effective coupling of the liquid cavity resonance with the self-resonance of the piston transducer presents difficulties, resulting in significant fluctuations in the transmitting voltage response (TVR) within the operating frequency band. The physical mechanism behind this phenomenon remains unclear to date. In this paper, a distributed parameter model (DPM) for the cavity-loaded piston transducer is proposed. The admittance, amplitude and phase of the vibration velocity and TVR of the transducer are calculated using both DPM and finite element method (FEM). The results from DPM and FEM exhibit good agreement, indicating that the DPM can accurately describe the vibration characteristics of the transducer. Finally, two physical analogies of the transducer are proposed and explanations for the large fluctuations in TVR are given. This study reveals the modal coupling mechanism of the cavity-loaded piston transducer, and provides theoretical support for the analysis and designs of such transducers.

Modeling and experimental investigation of multilayer DE transducers considering the influence of the electrode layers

Modeling and experimental investigation of multilayer DE transducers considering the influence of the electrode layers

Decoupled structure for improved adaptability of end-to-end models

Although end-to-end (E2E) trainable automatic speech recognition (ASR) has shown great success by jointly learning acoustic and linguistic information, it still suffers from the effect of domain shifts, thus limiting potential applications. The E2E ASR model implicitly learns an internal language model (LM) which characterises the training distribution of the source domain, and the E2E trainable nature makes the internal LM difficult to adapt to the target domain with text-only data. To solve this problem, this paper proposes decoupled structures for attention-based encoder–decoder (Decoupled-AED) and neural transducer (Decoupled-Transducer) models, which can achieve flexible domain adaptation in both offline and online scenarios while maintaining robust intra-domain performance. To this end, the acoustic and linguistic parts of the E2E model decoder (or prediction network) are decoupled, making the linguistic component (i.e. internal LM) replaceable. When encountering a domain shift, the internal LM can be directly replaced during inference by a target-domain LM, without re-training or using domain-specific paired speech-text data. Experiments for E2E ASR models trained on the LibriSpeech-100h corpus showed that the proposed decoupled structure gave 15.1% and 17.2% relative word error rate reductions on the TED-LIUM 2 and AESRC2020 corpora while still maintaining performance on intra-domain data. It is also shown that the decoupled structure can be used to boost cross-domain speech translation quality while retaining the intra-domain performance.

Piezoelectric Transducers: Complete Electromechanical Model with Parameter Extraction.

This paper presents a complete electromechanical (EM) model of piezoelectric transducers (PTs) independent of high or low coupling assumptions, vibration conditions, and geometry. The PT's spring stiffness is modeled as part of the domain coupling transformer, and the piezoelectric EM coupling coefficient is modeled explicitly as a split inductor transformer. This separates the coupling coefficient from the coefficient used for conversion between mechanical and electrical domains, providing a more insightful understanding of the energy transfers occurring within a PT and allowing for analysis not previously possible. This also illustrates the role the PT's spring plays in EM energy conversion. The model is analyzed and discussed from a circuits and energy harvesting perspective. Coupling between domains and how loading affects coupled energy are examined. Moreover, simple methods for experimentally extracting model parameters, including the coupling coefficient, are provided to empower engineers to quickly and easily integrate PTs in SPICE simulations for the rapid and improved development of PT interface circuits. The model and parameter extractions are validated by comparing them to the measured response of a physical cantilever-style PT excited by regular and irregular vibrations. In most cases, less than a 5-10% error between measured and simulated responses is observed.

Electro-mechano-acoustical equivalent circuit model of z-structured piezoelectric transducer

To meet the demands of low frequency, small size, light weight and high power in the underwater application, a z-structured piezoelectric transducer (ZPT) is innovated, and its equivalent circuit representation is derived. In configuration, ZPT employs the bender beam to implement z-shaped structure for the compact design. In mechanics, ZPT utilizes the coupled longitudinal-bending vibration to produce a large output at a low frequency. In order to study the electro-mechano-acoustical behavior of ZPT, an equivalent circuit model is built based on the conception of analogy, and subsequently solved through the matrix-based methodology. The crux of this model lies in the derivation of the representation about the beam. The corresponding simulations indicate that the effect of the bender beam on ZPT is significant, and its connecting function and bending vibration makes it possible for ZPT to achieve the performance of compact structure and low frequency. The tests of the transducer prototype show that our ZPT has the size of Φ70 × 110 mm, the weight of ∼1.056 kg without housing and the transmitting voltage response (TVR) of 124.9 dB at the resonance frequency of 2.088 kHz. The experimental results show a good agreement with the equivalent circuit simulations of the ZPT. The benefits about low frequency, small size and light weight of the ZPT are attributed to its z-structured design and coupled longitudinal-bending vibration.

Distributed-Parameter Modeling of High-Power Giant Magnetostrictive Transducers Considering Permanent Magnetic Bias

Distributed-Parameter Modeling of High-Power Giant Magnetostrictive Transducers Considering Permanent Magnetic Bias

Design and optimization of a dual-port Helmholtz transducer for crosswell seismic survey

Given the limitations of conventional crosswell seismic sources, which struggle to reduce frequency by elongating the axial dimension of the transducer, this study introduces an innovative method for frequency reduction in such sources. The proposed approach entails adding metal end caps with orifices to the piezoelectric circular tube with both ends open. This modification transforms the originally cylindrical liquid cavity with both ends open into a dual-port Helmholtz liquid cavity. To begin with, the frequency reduction effect of the dual-port Helmholtz liquid cavity is theoretically demonstrated using the equivalent circuit method. Subsequently, the finite element method is employed to validate the accuracy of the equivalent circuit and to compare the radiation performance of the two transducer models. Further, the impact of the materials and structural parameters of end caps on the resonant frequency of the liquid cavity is investigated using the finite element method. Finally, four transducer prototypes are fabricated, and their conductance curves are tested in silicone oil to verify the feasibility of the proposed approach. The test results affirm that the dual-port Helmholtz transducer exhibits a lower resonant frequency of the liquid cavity, which aligns well with the simulation results. The proposed dual-port Helmholtz transducer offers a promising solution for achieving low-frequency emission in crosswell seismic sources. The research findings establish a solid theoretical foundation for the design and optimization of this transducer.

A Hybrid Actuator Model for Efficient Guided Wave based Structural Health Monitoring Simulations

Abstract Simulation has been recognized as a promising option to reduce the time and costs associated with determining Probability of Detection (POD) curves to demonstrate the performance of Guided Wave based Structural Health Monitoring (GW-SHM) systems. Time domain transient spectral finite element schemes have been used for large GW-SHM simulation campaigns, but the most common piezoelectric transducer model used for actuation, the pin force model, has limitations in terms of its range of validity. This is because the excitation frequency for the pin force model has only been validated far below the first electromechanical resonance frequency of the piezoelectric transducer mainly due to not considering the normal stress and dynamics of the transducer. As a result, the value of simulation tools for performance demonstrations may be limited. To address this limitation, this paper introduces a Hybrid Actuator Model that integrates frequency-dependent complex interfacial stresses in both the shear and normal directions, computed using finite elements. These surface stresses are compatible with time domain transient spectral finite element schemes, enabling their seamless integration without compromising the required performance for conducting intensive simulation campaigns. The proposed hybrid actuator model undergoes validation through a combination of simulation and experimental studies. Additionally, a comprehensive parametric study is conducted to assess the model's validity across a wide range of excitation frequencies. The results demonstrate the accurate representation of the transduction signal above the piezoelectric transducer's first free electromechanical resonance frequency.

Development of a Comprehensive Dynamic Model for Giant Magnetostrictive Transducers Considering Bias Magnetic Field

Development of a Comprehensive Dynamic Model for Giant Magnetostrictive Transducers Considering Bias Magnetic Field

Experimental full waveform inversion for elastic material characterization with accurate transducer modeling

For quality assurance and in-service safety, sufficient characterization of the materials is essential during the development, manufacture, and processing of a material in any industrial setting. Evaluation of elastic coefficients, material microstructures, morphological features, and related mechanical properties are all part of the process of characterizing a material. Ultrasonic signals are sensitive to material properties such as wave speeds, attenuation, diffusion backscattering, microstructural variation, and elastic characteristics (e.g., elastic modulus, hardness, etc.). Ultrasonic computed tomography (USCT) is an emerging imaging method that can be implemented to obtain a quantitative estimation of material properties. In this study, a source estimation technique was initially proposed to obtain the source time function for accurate forward modeling by constructing a linear inverse problem for the unknown transducer modeling. Finally, a material characterization approach was proposed with accurate source estimation to extract wave speed distribution from an elastic material by employing a wave-based method, known as full waveform inversion (FWI). Systematic performance analysis of the proposed FWI model with accurate source estimation was assessed using experimental and synthetic data obtained from a 6061 aluminum sample. Overall, the proposed FWI technique has successfully reconstructed the wave speed distribution, exhibiting the potential of the proposed method of material characterization in various engineering applications.

Modeling and Simulation of Graphene-Based Transducers in NEMS Accelerometers.

The mechanical characteristics of graphene ribbons with an attached proof mass that can be used as NEMS transducers have been minimally studied, which hinders the development of graphene-based NEMS devices. Here, we simulated the mechanical characteristics of graphene ribbons with an attached proof mass using the finite element method. We studied the impact of force, residual stress, and geometrical size on displacement, strain, resonant frequency, and fracture strength of graphene ribbons with an attached proof mass. The results show that the increase of width and thickness of graphene ribbons would result in a decrease of the displacement and strain but also an increase of resonant frequency. The increase of the length of graphene ribbons has an insignificant impact on the strain, but it could increase the displacement and decrease the resonant frequency. The increase of residual stress in the graphene ribbons decreases its strain and displacement. The estimated fracture strength of graphene shows limited dependence on its thickness, with an estimated value of around 148 GPa. These findings contribute to the understanding of the mechanical characteristics of graphene ribbons with an attached proof mass and lay the solid foundation for the design and manufacture of high-performance graphene-based NEMS devices such as accelerometers.

Multidomain modeling of acoustical transducers and arrays using electrical network theory

Modeling of piezoceramic acoustic transducers involves the transformation of energy in the electrical, mechanical, acoustical radiation domains. By using generalized coordinates and Lagrangian mechanics, in which principle of least action is applied in each domain, the electrical, piezoelectric, mechanical and sound radiation problems can be solved separately and then combined in a multi-contour equivalent electro-mechanical circuit with each mechanical vibrational resonant modes representing separate degrees of freedom in the coupled electrical circuit. This energy approach involves the calculation of the potential and kinetic energies of each practical mode of vibration, which can be determined analytically, experimentally, or by finite-element-analysis. This is an alternative to the use of Newtonian mechanics which requires an accurate description of the real boundary conditions in the device and is common in many FEA modeling approaches. The availability of software (e.g., Matlab, Python, LTSpice, etc.) to model electrical circuits (networks in the case of multi-resonant devices) makes for a powerful and efficient modeling approach. The historical emergence of this approach stems from adapting the Rayleigh-Ritz method for mechanical and electrical domains with the advent of piezoelectric and magnetostrictive bodies. Several example of piezoceramic transducers are presented.

Introduction to the Technical Committee on Engineering Acoustics

This talk will introduce ongoing work in the Technical Committee on Engineering Acoustics (TCEA) of the Acoustical Society of America. Engineering Acoustics encompasses the theory and practice of creating tools to generate and investigate acoustical phenomena and then to apply the knowledge of acoustics to practical utility. This includes the design and modeling of acoustical and vibrational transducers, transducer arrays, and transduction materials or systems in all media and frequency ranges. It is also concerned with the design of acoustical instrumentation, metrology, and the calibration of those systems. It further considers all aspects of measurement, fabrication, and computational techniques as they relate to acoustical phenomena and their utility. The talk will provide an introduction of a broad range of research topics in TCEA, with specific highlights on exciting new areas of research.

Coupled models for designing and predicting performance of active sonar systems

Active sonar systems used to survey and image the seafloor typically transmit a pulse on a projector, receive echoes on an array of hydrophones, and condition and digitize the signals using on-board electronics. The quality of the data produced by these sensors is a function of the transducers, the electronics, and the environment. Simultaneous modeling of all these factors is necessary for accurate prediction of the system performance. Data products from these systems are often uncalibrated because absolute calibration is not required for their applications. However, modeling active sonar systems in their natural units within each domain provides clear benefits such as allowing system limitations to be accurately identified early during the design phase and easing validation of system performance in comparison with experimental data. This presentation will discuss the use of coupled multi-domain models in the design of two active sonar systems: the Sediment Volume Search Sonar and a multibeam echosounder architecture based on sigma-delta conversion. By coupling electro-mechanical transducer models and electrical hardware models with the Point-based Sonar Signal Model (PoSSM), it was possible to identify critical design parameters and sensitivities in the design of these sensors.

Design consideration on integration of mechanical intravascular ultrasound and electromagnetic tracking sensor for intravascular reconstruction

PurposeConsidering vessel deformation, endovascular navigation requires intraoperative geometric information. Mechanical intravascular ultrasound (IVUS) with an electromagnetic (EM) sensor can be used to reconstruct blood vessels with thin diameter. However, the integration design should be evaluated based on the factors affecting the reconstruction error.MethodsThe interference between the mechanical IVUS and EM sensor was measured in different relative positions. Two designs of the integrated catheter were evaluated by measuring the reconstruction errors using a rigid vascular phantom.ResultsWhen the distance from the EM sensor to the field generator was 75 mm, the interference from mechanical IVUS to an EM sensor was negligible, with position and rotation errors less than 0.1 mm and 0.6°, respectively. The reconstructed vessel model for proximal IVUS transducer had a smooth surface but an inaccurate shape at large curvature of the vascular phantom. When the distance to the field generator was 175 mm, the error increased significantly.ConclusionPlacing the IVUS transducer on the proximal side of the EM sensor is superior in terms of interference reduction but inferior in terms of mechanical stability compared to a distal transducer. The distal side is preferred due to better mechanical stability during catheter manipulation at larger curvature. With this configuration, surface reconstruction errors less than 1.7 mm (with RMS 0.57 mm) were achieved when the distance to the field generator was less than 175 mm.