Tonpilz Transducer Research Articles

Simulation and fabrication of a 20 kHz single-beam transducer

Abstract With the vigorous development of underwater acoustic technology in China, underwater acoustic transducers are constantly moving towards broadband, low-frequency, and high-power directions. How to obtain piezoelectric transducers with lower frequencies is still a research direction that scholars from various countries are striving to study. This article mainly studies and manufactures a 20 kHz single-beam piezoelectric transducer, using the classic Tonpilz transducer structure. Firstly, the Tonpilz transducer is theoretically analyzed using the classical equivalent circuit method. Secondly, the transducer is analyzed using ANSYS finite element analysis software to study the influence of piezoelectric ceramics on the frequency of the transducer, and the size of the piezoelectric ceramics is optimized to determine the size of the piezoelectric ceramic structure of the transducer. The working frequency of the transducer was calculated using software, and it was determined that the working frequency was approximately 20 kHz.

Design and development of a high-power wideband multimode Tonpilz transducer for underwater applications

Design and development of a high-power wideband multimode Tonpilz transducer for underwater applications

Experimental investigation of a Tonpilz transducer operating in the frequency band of 20-80 kHz (L).

The drive-stack design principle for the Tonpilz transducer aiming to transmit the acoustic signal in an ultra-wideband has been proposed [(2023). J. Acoust. Soc. Am. 154, 3709-3725], in which the design method is obtained and validated through simulation. This letter presents the experimental investigation of a fabricated transducer prototype and gives the measurement results of electroacoustic performance, including the electrical admittance, transmitting voltage response, directivity beam pattern, electroacoustic efficiency, and source level. The results indicate that the transducer can operate in the frequency band from 20 to 80 kHz without deep response notches within the band.

Bandwidth extension of the Tonpilz transducer using high-order longitudinal vibrations

Tonpilz transducers mainly work near the first-order longitudinal resonance. Until now, the cognition, research, and application of third-order resonance and above are still inadequate. By coupling the first-order resonance with other high-order resonances, it is possible to extend the bandwidth of the Tonpilz transducer to more than two octaves. Three difficulties hinder the achievement of the ultra-wideband, including how to activate consecutive high-order resonances, how to eliminate the response notches between resonances, and how to control the response values of resonances to reduce band fluctuation. This paper addresses these key issues. The results show that the number, position, length, and applied voltage of the drive-stack all significantly affect the band. We finally propose a drive-stack design principle that can activate the first four longitudinal resonances with close response values to be coupled to form the ultra-wideband. When applying this principle to the Tonpilz transducer, many variables need to be optimized. To solve this problem, an efficient and accurate optimization technology is proposed, consisting of simulated annealing initial optimization and finite element re-optimization, through which an ultra-wideband covering the frequency range of 19.5–90 kHz is obtained, verifying the effectiveness of the proposed principle. The designed transducer has three drive-stacks, and the band contains four longitudinal resonances.

Broadband Impedance Matching and Residual Vibration Attenuation for Underwater Acoustic Tonpilz Transducers Based on Adaptive Gauss–Newton Algorithm

Broadband Impedance Matching and Residual Vibration Attenuation for Underwater Acoustic Tonpilz Transducers Based on Adaptive Gauss–Newton Algorithm

Design and calibration of a Tonpilz transducer for low frequency medical ultrasound tomography.

The design and performance of a transducer for low frequency ultrasound tomography is presented, motivated by recent research demonstrating that acoustic waves transmitting at frequencies between 10 kHz and 750 kHz penetrate the lungs and may be useful for thoracic imaging. An adaptation of the traditional Tonpilz design was developed, vibrational amplitude and electrical impedance were measured, and an optimal frequency was determined. The design is found to meet the desired mechanical, electrical, and safety specifications. Thus, it was considered a promising option for the target application of pulmonary imaging with ultrasound computed tomography between 50 and 200 kHz; highest efficiency achieved around 125 kHz and 156 kHz, and beam divergence of 40°.

Balanced truncation for reduced‐order modeling of Piezoelectric Tonpilz Transducer on the limited frequency interval

Piezoelectric based Tonpilz Transducer is a mechatronics control device that works on high-power sound propagation to navigate or detect objects under the water. In order to analyze the design and performance, we generate a mathematical model of such apparatus by applying the finite element method, which yields a large-scale sparse index-I descriptor system. We also study low-rank Gramian factors based on Balanced Truncation to obtain the reduced-order model for efficient design on the limited frequency domain. The low-rank Gramian factors are obtained by solving a pair of frequency-limited Lyapunov equations. We have modified the low-rank Alternative Direction Implicit method to solve the Lyapunov equations for retaining sparsity and ensuring the preservation of the structure of the system matrices. Numerical analyses are conducted to validate the proposed techniques, and the reduced order physical model is regenerated for a comparative physical analysis with the full dimensional physical model.

Equivalent circuit for analyzing the transmitting characteristics of multimode Tonpilz transducer.

Multimode Tonpilz transducers operate at longitudinal and flexural vibration modes simultaneously. Consequently, they have wider bandwidths than conventional single-mode transducers. Generally, the performance of Tonpilz transducers is analyzed using the finite element method (FEM), whereas the equivalent circuit method (ECM) has proven to be a fast and efficient alternative to the FEM. However, the ECM for analyzing the acoustic characteristics of multimode Tonpilz transducers has not yet been developed. To address this issue, an equivalent circuit for the multimode Tonpilz transducer is developed herein. The proposed ECM encompasses the flexural characteristics of the Tonpilz head mass, which is impossible with conventional equivalent circuits. Furthermore, a prototype of the multimode Tonpilz transducer was fabricated to verify the validity of the developed ECM. Additionally, the accuracy and compliance of the ECM were confirmed by comparing the measured performance of the transducer with that from the equivalent circuit analysis.

Design, development and characterization of a mid-frequency (35 khz) tonpilz transducer array from 0.675PMN-0.325PT piezoceramics

A mid-frequency tonpilz transducer array was designed and analyzed by finite element method using commercial ATILA code and constructed using piezoceramic rings with lead magnesium niobate (PMN)-lead titanate (PT) composition. The morphotropic phase boundary (MPB) 0.675Pb(Mg1/3Nb2/3)O3-0.325PbTiO3 composition was chosen to obtain higher performance from the transducer due to the superior dielectric and electromechanical properties of the MPB compositions. A pure perovskite phase was obtained from the ceramics. Piezoelectric charge coefficient (d33) was measured as 435 pC×N-1. Single tonpilz element and an array consisting of 7-unit array were constructed and later potted in polyurethane for underwater measurements. A second array was also constructed for comparison from commercial hard Pb(Zr,Ti)O3-PZT ceramics. The longitudinal piston mode vibration frequency of the tonpilz transducer was measured around 33 kHz in air and around 35 kHz in water. The PMN-PT based array was found to have a comparable transmit performance and a superior receive performance compared to PZT.

SPICE Modeling of a High-Power Terfenol-D Transducer Considering Losses and Magnetic Flux Leakage.

Of great importance is modeling for transducer design and application to predict its performance and simulate key characteristics. The equivalent circuit modeling (ECM), one of the most powerful tools, has been widely used in the transducer industry and academia due to its outstanding merits of low simulation cost and easy usage for multi-field simulation in both time and frequency domains. Nevertheless, most of the existing equivalent circuit models for Terfenol-D transducers normally ignore three material losses, namely elastic loss, piezomagnetic loss, and magnetic loss. Additionally, the magnetic leakage due to the intrinsic poor magnetic permeability of Terfenol-D is rarely considered into the piezomagnetic coupling. Both loss effects will produce substantial errors. Therefore, an improved SPICE model for a high-power Terfenol-D transducer considering the aforementioned three losses and magnetic flux leakage (MFL) is proposed in this article, which is implemented on the platform of LTspice software. To verify the usefulness and effectiveness of the proposed technique, a high-power Terfenol-D tonpilz transducer prototype with a resonance frequency of around 1 kHz and a maximum transmitting current response (TCR) of 187.1 dB/1A/ μ Pa is built and tested. The experimental results, both in the air and water of the transducer, are in excellent agreement with the simulated results, which well validates our proposed modeling methods.

Comparison of the performance characteristics of the tonpilz transducers fabricated from 0.60PMN-0.40PT & PZT piezoceramics

In this study, tonpilz transducers based on 0.60Pb(Mg1/3Nb2/3)O3-0.40PbTiO3 (60PMN-PT) and commercially available lead zirconate titanate (PZT) compositions (PZT 4, PZT 5H, PZT 8 and PZT 5A) were designed, fabricated, characterized and compared for their underwater performance. Each stack is composed of two rings of PZT or PMN-PT ceramics. Transducers were designed and analyzed using the commercial ATILA finite elements analysis (FEA) code. Commercially available powders were used for PZT, whereas 60PMN-PT powders with pure perovskite phase were synthesized using solid-state reaction route. Ceramic rings have been produced using dry pressing. Dielectric, piezoelectric and electromechanical properties of the rings were calculated using the resonance method. Vibration modes of the rings and transducers constructed from various types of piezoceramics were analyzed using FEA. The main resonance frequency of the tonpilz transducer belonging to the longitudinal piston mode was measured in the mid-frequency range between 30 and 35 kHz. Underwater acoustic measurements were conducted on polymer-coated transducers, and their performances were compared for possible underwater acoustic applications. Transducers fabricated from 60PMN-PT were found to have comparable underwater performance with that of PZT 4, where the Transmitting Voltage Response (TVR) reached 135 − 136 dB re 1 µPa/V @1 m range with a −3dB bandwidth of 4 kHz. These results indicated the viability of using 60PMN-PT ceramics in active device applications in an array form.

Influences of length and position of drive-stacks on the transmitting-voltage-response of the broadband Tonpilz transducer.

Most broadband Tonpilz transducers are achieved by coupling first-order longitudinal mode with other modes introduced by an elaborately designed structure (e.g., flexural mode of the head mass). To further expand the bandwidth is difficult and, even if successful, inevitably makes the structure more complex. Longitudinal modes are the inherent vibration modes of rod-shaped Tonpilz transducers. Using high-order longitudinal modes to achieve broadband performance can retain the simple structure similar to the conventional Tonpilz transducer. However, activating continuous, equal-amplitude longitudinal modes is not easy. The longitudinal length and position of the drive-stacks have significant influences on the generation of resonances and their vibration amplitude. In this paper, these influences are studied using the equivalent circuit method for a rod transducer having two drive-stacks, and finally we provide the drive-stack arrangement that can activate the first-three longitudinal modes to obtain the desired broadband response effectively. We also find that the response value of resonances can be balanced to reduce band fluctuation by adjusting drive lengths. The design procedure for the broadband Tonpilz transducer is proposed. The finite element method is used to design broadband transducers having bandwidth greater than one octave following the procedure. A transducer prototype with a simple structure is fabricated and measured to verify the validity of the proposed method.

A wideband tonpilz transducer with a transverse through-hole in the radiating head.

We propose a rectangular transverse through-hole wideband tonpilz transducer using multimode coupling. To excite a vibration mode that can be coupled with the longitudinal vibration for broadening the frequency band, a rectangular through-hole is opened at a certain distance from the front head of the conventional longitudinal vibration tonpilz transducer. To achieve the best bandwidth, the finite element method was used to optimize the length and width of the through-hole and the distance between the front end of the hole and the end surface of the front head. In addition, to obtain the best hole position and size, a prototype tonpilz transducer was developed. The test results show that the transducer has three main operating modes within 12-32.5 kHz, and the latter two modes contribute to the widening of operating bandwidth. A longitudinal vibration tonpilz transducer of the same size with no hole has a 3 dB bandwidth of only 3 kHz, whereas the holed transducer has a bandwidth of 10.5 kHz. Effectively expanding the working bandwidth shows that the theoretical calculations and experimental results are in good agreement.

Design of wideband tonpilz transducers for underwater SONAR applications with finite element model

This paper describes the designing and optimization of tonpilz type transducers based on number of layers, width and thicknesses and type of active materials, dimensions of head and tail mass by exploiting finite element models for their effective and optimized usage in underwater SONAR applications. Geometry parameters of tonpilz transducers have been studied in terms of active piezoelectric stack and associated components comprised of head and tail masses and optimized structure is explored. Piezoelectric stack including piezoceramic material (PZT-4) and single crystal (PMNPT), is utilized for underwater acoustic generation, while Aluminum is taken as head mass and highly attenuated material stainless steel is used for tail mass. Performance of tonpilz transducer has been investigated and evaluated in terms of total radiating power (TRP), transmitting voltage response (TVR), directivity index and specific acoustic impedance for all designed structures. Comparison is carried out for the optimized structure that provides high sensitive frequency region in form of constant TVR and maximum sound directivity used for accurate under water detection applications. TVR in the sensitive region using PMNPT as the stack material shows enhanced results as compared to PZT-4. Sound intensity level in terms of TRP peaks also rises with a greater number of layers for both PMNPT and PZT-4 driving stack materials. Furthermore, it has been observed that Driving stack material is more effective than the other components of Tonpilz transducer because it effects the flat response and also enhances the TVR response. Secondly, head mass of the Tonpilz transducer is more effective than the remaining because resonance and flexural frequency depend on it.

Analysis of the effect of radiating surface geometry on the beam pattern of underwater acoustic transducers

Piston-type underwater acoustic transducers are used individually as well as in arrays for various acoustic applications. Circular pistons, in particular, are widely used in arrays. However, the performance of an array with circular pistons is restricted due to the limited edge contact of the circular geometry, which in turn limits the radiating power of the array. In this study, the radiation characteristics of other common piston geometries that can readily overcome the edge contact limitation of the circular piston were theoretically investigated and compared with each other. The pistons considered include those with circular, square, hexagonal, and octagonal radiating surfaces. The analysis results confirmed that, for smaller pistons with an equivalent circular diameter less than a half wavelength, the effect of the radiation surface geometry is insignificant. As such, pistons of the other shapes can be used to overcome the limitation of the circular piston without deteriorating the radiation characteristics of the array, which opens up many possibilities regarding the design of underwater acoustic piston arrays. The validity of the theoretical analysis was verified through the finite element analysis and experimental measurement of the radiation pattern of a prototype Tonpilz transducer with an octagonal head mass.

Design of a Wideband Tonpilz Transducer Comprising Non-Uniform Piezoceramic Stacks with Equivalent Circuits.

Tonpilz transducers are desirable for their superior performance in underwater target detection and communication applications. Several design schemes to widen their bandwidth have been reported, but these schemes often involve a complex structure or arrangement of additional components. In this study, a simple design is proposed to improve the bandwidth of a multimode Tonpilz transducer by using a non-uniform drive section that consists of piezoelectric stacks of various thicknesses. The efficacy of the design is illustrated with a multimode Tonpilz transducer having three lead zirconate titanate (PZT) stacks of different thicknesses. A new equivalent circuit was developed to analyze the frequency response of the transducer incorporating the non-uniform drive section and was used for rigorous analysis of the effects of varying the position and thickness of the non-uniform stacks on the transmitting characteristics of the transducer. The validity of the design was verified through the fabrication and characterization of a prototype multimode Tonpilz transducer. The developed structure can be readily extended to an arbitrary number of stacks in the Tonpilz transducer with any number of PZT disks in each stack.

Tonpilz transducer head mass selection based on excitation signal type

The head mass as front-end material is an essential component of Tonpilz transducers. The transmission mechanism of head mass under excitations of continuous wave and short pulse are investigated in order to maximize the transducer acoustic radiation power. In the case of continuous wave excitation, it was found that the role of the head mass is to change the effective vibration velocity, and the transmitting voltage response is proportional to the characteristic impedance of the head mass. In the case of short pulse excitation, the head mass acts as a medium layer, and the highest acoustic radiation power appears when the characteristic acoustic impedance of head mass matches that of water medium. Our results provide deeper insight on the Tonpilz transducer design mechanism, and useful selection rules for the front-end material under different types of excitation signals.

Analysis of the transmitting characteristics of an acoustic conformal array of multimode tonpilz transducers by the equivalent circuit method

Commonly used underwater acoustic array types include planar and conformal arrays. The conformal array is favorable in practical active sonar systems as it offers superior acoustic performance, but its relatively complicated structure requires sophisticated analysis and design. In general, the characteristics of the array are analyzed using the finite element method (FEM). However, for complicated structures like the conformal array, the FEM is extremely time consuming and computation intensive. In this work, we developed a new equivalent circuit method (ECM) that can facilitate the analysis of the acoustical performance of a conformal array. The proposed ECM can include the effect of mutual interference between constitutive elements of the conformal array in addition to its own property of the array, which has not been possible with conventional equivalent circuits. The new ECM was applied to the analysis of the transmitting characteristics of a conformal array of multimode Tonpilz transducers. The Tonpilz transducer operated at both longitudinal- and flexural-mode resonances simultaneously to achieve a wide bandwidth. A new equivalent circuit to represent the multimodal properties of the Tonpilz transducer itself was derived as well. The validity and efficiency of the analysis of the Tonpilz transducer and the conformal array was verified by comparing the transmitting voltage response spectrum obtained by the ECM with those obtained by the FEM and experimental measurement. For the experimental validation, prototypes of the multimode Tonpilz transducers and their conformal array were fabricated and characterized.

Modeling and Design of a Rear-Mounted Underwater Projector Using Equivalent Circuits.

Tonpilz is a popular transducer for underwater projector arrays for sonar systems. For low-frequency transmission, a larger axial dimension of the conventional Tonpilz transducer is required. However, a bulky and heavy Tonpilz element is not suitable due to limitations in terms of the space and payload of the array platform. To address this problem, we developed a rear-mounted Tonpilz transducer to generate a sub-fundamental resonance in addition to the common longitudinal resonance. For this purpose, we developed a new equivalent circuit model that can reflect all the effects of the key design parameters of the transducer, such as suspension thickness (stiffness), tail mass thickness, and head mass thickness. The impedance and transmitting voltage response were evaluated as performance factors at both resonance frequencies. The validity of the circuit was verified by comparing the analysis results with those from the finite element analysis of the same transducer. Based on the results, the transducer structure was designed to have comparable transmitting performance at both resonance frequencies by employing relatively high suspension stiffness, light tail mass, and heavy head mass. The novel design can permit the dual-band operation of the transducer so that the transducer can operate as a wideband projector.

Optimization and characterization of a wideband multimode Tonpilz transducer for underwater acoustical arrays

A multimode underwater acoustical transducer is well-known for providing wider bandwidth than a conventional single-mode transducer. However, the design of a low-frequency multimode transducer to achieve the desired wideband characteristics for an underwater array is challenging when considering the array’s size and weight limitations. Therefore, this study focused on the development of a multimode transducer structure for superior wideband characteristics. The effect of various structural parameters on the performance of the multimode Tonpilz transducer was first analyzed with emphasis on its bandwidth using the finite element method (FEM). Then, the structure of the transducer was improved by analyzing the effect of the side acoustic window and incorporating realistic design considerations. Finally, the improved transducer structure was optimized to have the widest possible bandwidth while maintaining its transmitting voltage response (TVR) level over a typical power requirement. The final design was validated by fabricating a prototype transducer and evaluating its acoustical performance.