@article{59995,
abstract = {{Abstract
Ultrasonic transmission measurements can be used for material characterization, as the propagation time of sound waves and thus their velocity depends on the elastic material parameters. Measurement results for the elastic material parameters are acquired non-destructively using ultrasonic transmission measurements of hollow cylindrical polymer specimens. To determine the material parameters, an inverse approach is used comparing measurements with simulated data. Previous studies show that the procedure exhibits low sensitivity with respect to the shear parameters of the material. In order to increase the sensitivity, we propose to apply a spatially annular excitation on the base of the specimen. As a measure to analyse the sensitivities with respect to all parameters and their linear independence, we observe the volume of the parallelotope of the sensitivity vectors. Here, a scaled boundary finite element formulation of wave propagation in the specimen is expanded to yield derivative information directly, and a sensitivity analysis can be carried out efficiently. Finally, the results of this sensitivity analysis with regard to the annular excitation are also applied to the measurement setup.}},
author = {{Dreiling, Dmitrij and Itner, Dominik and Gravenkamp, Hauke and Claes, Leander and Birk, Carolin and Henning, Bernd}},
issn = {{0957-0233}},
journal = {{Measurement Science and Technology}},
keywords = {{Sensitivity analysis, Ultrasonic transducer, Guided waves, Polymers, Gram determinant}},
publisher = {{IOP Publishing}},
title = {{{Increasing the sensitivity of ultrasonic transmission measurements for elastic material parameter estimation}}},
doi = {{10.1088/1361-6501/add9b6}},
volume = {{36}},
year = {{2025}},
}
@inproceedings{64798,
abstract = {{Lead-containing piezoelectric ceramics are still the base for today’s ultrasonic transducers used in broad applications. This is partly due to missing powerful lead-free piezoelectric ceramic parts in the commercial market. There has been much research on lead-free materials but developing them into marketable parts seems to be an ongoing process. The actual exemption of ROHS has expired, but as the new exemption has already been requested, ceramic suppliers keep on selling lead containing products. Nevertheless, these should be replaced by lead-free alternatives for environmental and health issues.
This contribution focuses on exploring the technological readiness level of lead-free hard piezoceramics for prestressed ultrasonic transducers. A small series of bolted Langevin transducers was set up with standard PZT material and three commercial lead-free variants. Results of the building process from individual ring ceramic characteristics to transducer load tests are presented. The main finding of this study is that the lead-free materials technically can compete with the standard PZT for medium-power applications. Some adaptations in the ultrasonic system must be done: the geometry must be altered to fit resonance frequency, and higher voltages or thinner ceramics are needed to achieve the same vibration level at low load. For reaching same power, the volume of lead-free ceramics must be 1.5 to 3 times larger. As already promoted in literature, mechanical losses at high vibration levels are smaller for the lead-free materials. This might help to argument lead-free piezoelectric materials in some applications.
References
1. Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011 on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment. EUR-Lex Document 02011L0065-20240801. Available online: http://data.europa.eu/eli/dir/2011/65/2024-08-01 (accessed on 24 January 2025).
2. Langevin, P. (1918) Method and Apparatus for Transmitting and Receiving Submarine Elastic Waves Using the Piezoelectric Properties of Quartz. French Patent Office; Patent No. FR505703.
3. Hemsel, T.; Twiefel, J. (2023) Piezoelectric Ultrasonic Power Transducers. In Encyclopedia of Materials: Electronics; Academic Press: Oxford, UK; pp. 276–285. https://doi.org/10.1016/b978-0-12-819728-8.00047-4.
4. ATHENA Technologie Beratung GmbH (2025) Description of Ultrasound Generator. Available online: http://shop.myathena.de/epages/12074748.sf/de_DE/?ObjectPath=/Shops/12074748/Products/AM200 (accessed on 13 January 2025).
5. Littmann, W.; Hemsel, T.; Kauczor, C.; Wallaschek, J.; Sinha, W. (2003) Load-adaptive phase-controller for resonant driven piezoelectric devices. Proc. World Congr. Ultrason. 2003, 48, 547–550.
6. Scheidemann, C., Bornmann, P., Littmann, W., & Hemsel, T. (2025). Lead-Free Ceramics in Prestressed Ultrasonic Transducers. Actuators, 14(2), 55. https://doi.org/10.3390/act14020055
}},
author = {{Scheidemann, Claus and Bornmann, Peter and Littmann, Walter and Hemsel, Tobias}},
keywords = {{lead free piezoelectric ceramics, bolted Langevin transducer, medium power ultrasound.}},
location = {{Vilnius, Lithuania}},
title = {{{Bolted Langevin transducers with leadfree piezoelectric ceramics}}},
year = {{2025}},
}
@article{51518,
abstract = {{In applications of piezoelectric actuators and sensors, the dependability and particularly the reliability throughout their lifetime are vital to manufacturers and end-users and are enabled through condition-monitoring approaches. Existing approaches often utilize impedance measurements over a range of frequencies or velocity measurements and require additional equipment or sensors, such as a laser Doppler vibrometer. Furthermore, the non-negligible effects of varying operating conditions are often unconsidered. To minimize the need for additional sensors while maintaining the dependability of piezoelectric bending actuators irrespective of varying operating conditions, an online diagnostics approach is proposed. To this end, time- and frequency-domain features are extracted from monitored current signals to reflect hairline crack development in bending actuators. For validation of applicability, the presented analysis method was evaluated on piezoelectric bending actuators subjected to accelerated lifetime tests at varying voltage amplitudes and under external damping conditions. In the presence of a crack and due to a diminished stiffness, the resonance frequency decreases and the root-mean-square amplitude of the current signal simultaneously abruptly drops during the lifetime tests. Furthermore, the piezoelectric crack surfaces clapping is reflected in higher harmonics of the current signal. Thus, time-domain features and harmonics of the current signals are sufficient to diagnose hairline cracks in the actuators.}},
author = {{Aimiyekagbon, Osarenren Kennedy and Bender, Amelie and Hemsel, Tobias and Sextro, Walter}},
issn = {{2079-9292}},
journal = {{Electronics}},
keywords = {{piezoelectric transducer, self-sensing, fault detection, diagnostics, hairline crack, condition monitoring}},
number = {{3}},
publisher = {{MDPI AG}},
title = {{{Diagnostics of Piezoelectric Bending Actuators Subjected to Varying Operating Conditions}}},
doi = {{10.3390/electronics13030521}},
volume = {{13}},
year = {{2024}},
}
@inbook{33500,
abstract = {{This article is dedicated to piezoelectric ultrasonic power transducers that differ to well known medical ultrasonic diagnostic apparatus or non destructive testing devices by the level of power in use; typically several tens of up to more than thousand watts are used in a multitude of different applications. After a short introduction including historical development, the first focus is on theoretical background of the operating principle, design and mechanical modeling. As piezoelectric elements transform electrical to mechanical energy and vice versa, equivalent circuit modeling is also described. After that, sample applications are delineated by the matter wherein ultrasound generates unique effects: incredible high pressure level as well in air as in water, micro-bubbles generating temperature peaks for very short time instances in fluids, acoustoplastic effect, enhancement of diffusion and recrystallization in solids, friction manipulation, incremental deformation and micro-cracking of surfaces, or even generation of macroscopic movements in motors. At the end, some future directions ranging from novel modeling approaches to advanced control and new materials are addressed.}},
author = {{Hemsel, Tobias and Twiefel, Jens}},
booktitle = {{Reference Module in Materials Science and Materials Engineering}},
isbn = {{978-0-12-803581-8}},
keywords = {{Equivalent circuit model, Langevin transducer, Lumped parameter model, Piezoelectric transducer, Ultrasonic processes, Ultrasound}},
publisher = {{Elsevier}},
title = {{{Piezoelectric Ultrasonic Power Transducers}}},
doi = {{10.1016/b978-0-12-819728-8.00047-4}},
year = {{2022}},
}
@article{6551,
author = {{Bause, Fabian and Rautenberg, Jens and Feldmann, Nadine and Webersen, Manuel and Claes, Leander and Gravenkamp, Hauke and Henning, Bernd}},
journal = {{Measurement Science and Technology}},
keywords = {{material characterization, material parameters, acoustic waveguide, daming, ultrasonic transducer}},
number = {{10}},
title = {{{Ultrasonic transmission measurements in the characterization of viscoelasticity utilizing polymeric waveguides}}},
doi = {{10.1088/0957-0233/27/10/105601}},
volume = {{27}},
year = {{2016}},
}
@inproceedings{13222,
abstract = {{When performing measurements, the effects of the measurement system itself on the measured data generally must be eliminated. Consequently, those effects, i.e. the system’s dynamic behavior, need to be known. For the piezo-composite transducers in an ultrasonic transmission line, a model based approach is used to describe their dynamic behavior and take into account its dependence on the environment temperature and the acoustic impedance of the target medium. Temperature-dependent model parameters are presented, which are obtained by performing a multiplepart identification process on the transducer model, based on electrical impedance measurements [1]. The identification process uses an inverse approach for optimizing a subset of the model parameters. Additionally, algorithmic differentiation methods are used to determine accurate derivatives. In a final optimization step, impedance measurements taken at different temperatures are used to determine the temperature dependencies of the model parameters. These can then be used to assess the plausibility of the identification results. Additionally, the parameters can be expressed as polynomials in the temperature to take different operating conditions into account.}},
author = {{Webersen, Manuel and Bause, Fabian and Rautenberg, Jens and Henning, Bernd}},
booktitle = {{AMA Conferences 2015}},
keywords = {{piezo-composite, transducer, temperature dependency, identification, plausibility}},
location = {{Nürnberg}},
pages = {{195--200}},
title = {{{Identification of temperature-dependent model parameters of ultrasonic piezo-composite transducers}}},
year = {{2015}},
}
@inproceedings{9783,
abstract = {{To optimize the ultrasound irradiation for cavitation based ultrasound applications like sonochemistry or ultrasound cleaning, the correlation between cavitation intensity and the resulting effect on the process is of interest. Furthermore, changing conditions like temperature and pressure result in varying acoustic properties of the liquid. That might necessitate an adaption of the ultrasound irradiation. To detect such changes during operation, process monitoring is desired. Labor intensive processes, that might be carried out for several hours, also require process monitoring to increase their reliability by detection of changes or malfunctions during operation. In some applications cavitation detection and monitoring can be achieved by the application of sensors in the sound field. Though the application of sensors is possible, this necessitates modifications on the system and the sensor might disturb the sound field. In other applications harsh, process conditions prohibit the application of sensors in the sound field. Therefore alternative techniques for cavitation detection and monitoring are desired. The applicability of an external microphone and a self-sensing ultrasound transducer for cavitation detection were experimentally investigated. Both methods were found to be suitable and easily applicable.}},
author = {{Bornmann, Peter and Hemsel, Tobias and Sextro, Walter and Maeda, Takafumi and Morita, Takeshi}},
booktitle = {{Ultrasonics Symposium (IUS), 2012 IEEE International}},
issn = {{1948-5719}},
keywords = {{cavitation, chemical reactors, microphones, process monitoring, reliability, ultrasonic applications, ultrasonic waves, acoustic properties, cavitation based ultrasound applications, cavitation intensity, change detection reliability, external microphone, malfunction detection reliability, nonperturbing cavitation detection, nonperturbing cavitation monitoring, process monitoring, self-sensing ultrasound transducer, sonochemical reactors, sonochemistry, ultrasound cleaning, ultrasound irradiation, Acoustics, Liquids, Monitoring, Sensors, Sonar equipment, Transducers, Ultrasonic imaging}},
pages = {{1141--1144}},
title = {{{Non-perturbing cavitation detection / monitoring in sonochemical reactors}}},
doi = {{10.1109/ULTSYM.2012.0284}},
year = {{2012}},
}
@article{9744,
abstract = {{Direct ultrasound irradiation is advantageous to increase the efficiency of the hydrothermal method which can be used for the production of piezoelectric thin films and lead free piezoelectric ceramics. To apply ultrasound directly to the process transducer prototypes were developed regarding the boundary conditions of the hydrothermal method. LiNbO$_{3}$ and PIC 181 were proven as feasible materials for high temperature resistant transducers ($\geq 200^\circ C$). Resistance of the transducers horn against the corrosive mineralizer was achieved by using Hastelloy C-22. The efficiency of the ultrasound assisted hydrothermal method depends on the generated sound field. Impedance and sound field measurements have shown that the sound field depends on the filling level and the position and design of the transducer.}},
author = {{Bornmann, Peter and Hemsel, Tobias and Littmann, Walter and Ageba, Ryo and Kadota, Yoishi and Morita, Takeshi}},
issn = {{1948-5719}},
journal = {{Journal of Korean Physical Society}},
keywords = {{High-temperature transducer, Hydrothermal method, Lithium-niobate transducer}},
number = {{4}},
pages = {{1122}},
title = {{{Ultrasonic Transducer for the Hydrothermal Method}}},
doi = {{10.3938/jkps.57.1122}},
volume = {{57}},
year = {{2010}},
}
@article{9745,
abstract = {{In the modeling of piezoelectric Langevin transducers using usual transfer matrix methods, some simplifications have been adopted. This leads to reduction of the model quality. A mixed transfer matrix method is employed in the modeling of Langevin transducers, where the pre-stressed bolt is modeled as a separate four-pole element, which is connected to other elements in parallel. Based on the mixed transfer matrix method, the four (six)-pole element description of the piezoelectric Langevin transducer is built up and the total transfer matrix relation is derived. The resonance frequencies of the transducer are calculated and then measured using the impedance analyzer (HP4192). Experimental result shows that the mixed transfer matrix method has better modeling quality than the usual transfer matrix method for the vibration analysis of piezoelectric Langevin transducers.}},
author = {{Fu, Bo and Li, Chao and Zhang, Jianming and Huang, Zhenwei and Hemsel, Tobias}},
issn = {{1948-5719}},
journal = {{Journal of Korean Physical Society}},
keywords = {{Piezoelectric langevin transducer, Transfer matrix method, Four (six)-pole element description, Pre-stressed bolt}},
number = {{4}},
pages = {{929}},
title = {{{Modeling of Piezoelectric Langevin Transducers by Using Mixed Transfer Matrix Methods}}},
doi = {{10.3938/jkps.57.929}},
volume = {{57}},
year = {{2010}},
}
@article{9749,
abstract = {{Piezoelectric materials find wide application in technical systems. Most often, a combination of piezoelectric and other materials is advantageous. The position and the amount of the piezoelectric material within the overall system depends on various aspects like maximum mechanical output to the load, maximum electromechanical efficiency of the system, maximum utilization of the piezoelectric material, minimum self-heating of the piezoelectric material, and controllability of the system, which might be key aspects for the optimisation of the system design. For a composite longitudinal vibrator (bolted Langevin transducer), which is a base for many technical applications, this contribution shows in detail, how above mentioned aspects depend on the position and volume of the piezoelectric material related to the mode shape.}},
author = {{Hemsel, Tobias and Lierk, Ernst Günther and Littmann, Walter and Morita, Takeshi}},
issn = {{1948-5719}},
journal = {{Journal of Korean Physical Society}},
keywords = {{Bolted Langevin transducer, Optimum placement of piezoelectric ceramics}},
number = {{4}},
pages = {{933--937}},
title = {{{Various Aspects of the Placement of a Piezoelectric Material in Composite Actuators, Motors, and Transducers}}},
doi = {{10.3938/jkps.57.933}},
volume = {{57}},
year = {{2010}},
}
@inproceedings{9568,
abstract = {{A simple pre-stress estimate method of Langevin transducers is studied. The measurement setup consists of a capacitor, an impedance converter and a voltmeter. Based on the piezoelectric equation and the basic circuit theory, the mathematical expression between the pre-stress and the voltage across the capacitor is derived. The pre-stress level can then be calculated out of the measurement of the capacitor voltage. In order to evaluate the precision of this method, a force washer is used to measure the pre-stress of the Langevin transducer. The result shows the pre-stress level obtained from this method is 30-40\% higher than the pre-stress level measured by the force washer. This method is simple and can be used to estimate the pre-stress of various Langevin transducers. The precision of this method can be raised if d33 is identified under different pre-stress levels.}},
author = {{Bo, Fu and Ting, Li and Hemsel, Tobias}},
booktitle = {{Piezoelectricity, Acoustic Waves, and Device Applications, 2008. SPAWDA 2008. Symposium on}},
keywords = {{capacitors, impedance convertors, piezoelectric transducers, stress analysis, Langevin transducers, basic circuit theory, capacitor, impedance converter, piezoelectric equation, pre-stress estimating method, voltmeter, Capacitors, Educational institutions, Equations, Force measurement, Impedance measurement, Manufacturing, Mechatronics, Piezoelectric transducers, Voltage, Voltmeters, Langevin transducer, capacitor, piezoelectric element, pre-stress}},
pages = {{324--327}},
title = {{{A simple pre-stress estimating method of langevin transducers}}},
doi = {{10.1109/SPAWDA.2008.4775801}},
year = {{2008}},
}
@article{9533,
abstract = {{The design of piezoelectric transducers is usually based on single-objective optimization only. In most practical applications of piezoelectric transducers, however, there exist multiple design objectives that often are contradictory to each other by their very nature. It is impossible to find a solution at which each objective function gets its optimal value simultaneously. Our design approach is to first find a set of Pareto-optimal solutions, which can be considered to be best compromises among multiple design objectives. Among these Pareto-optimal solutions, the designer can then select the one solution which he considers to be the best one. In this paper we investigate the optimal design of a Langevin transducer. The design problem is formulated mathematically as a constrained multiobjective optimization problem. The maximum vibration amplitude and the minimum electrical input power are considered as optimization objectives. Design variables involve continuous variables (dimensions of the transducer) and discrete variables (the number of piezoelectric rings and material types). In order to formulate the optimization problem, the behavior of piezoelectric transducers is modeled using the transfer matrix method based on analytical models. Multiobjective evolutionary algorithms are applied in the optimization process and a set of Pareto-optimal designs is calculated. The optimized results are analyzed and the preferred design is determined. }},
author = {{Fu, Bo and Hemsel, Tobias and Wallaschek, Jörg}},
issn = {{0041-624X}},
journal = {{Ultrasonics}},
keywords = {{Piezoelectric transducer}},
pages = {{e747 -- e752}},
title = {{{Piezoelectric transducer design via multiobjective optimization}}},
doi = {{10.1016/j.ultras.2006.05.087}},
volume = {{44, Supplement}},
year = {{2006}},
}