@inproceedings{65625,
  author       = {{Friesen, Olga and Hölscher, Jonas and Siegmund, Michael B. K. and Claes, Leander and Henning, Bernd}},
  title        = {{{Experimental and Numerical Investigation of Jump Phenomena in the Frequency Response of Piezoelectric Systems}}},
  year         = {{2026}},
}

@article{65785,
  abstract     = {{Simulation-based design of high-power ultrasonic systems depends on the accurate modelling of the electromechanical behaviour of piezoceramic materials. In practical transducer applications, the relevant operating points are influenced by mechanical preload and heating, both of which give rise to changes in the elastic, dielectric, and piezoelectric material properties. Material parameters identified under idealised, unloaded conditions are therefore insufficient to represent piezoceramic material behaviour under realistic operating conditions. To overcome this limitation, experimental setups are developed that enable the measurement of electrical impedance spectra under controlled thermal and mechanical conditions. The acquired impedance data are used in an inverse identification procedure, in which the behaviour of a finite element forward model is iteratively fitted to the measurements using a block coordinate descent optimisation strategy guided by a sensitivity analysis. This yields effective linear material parameters as a function of temperature and mechanical stress at varying operating points. The identified temperature-dependent parameters, for instance, can be employed in a coupled thermo-electromechanical simulation framework to predict the temperature-dependent material behaviour during operation. The linear identification based on varying operation points provides an initial approximation of the nonlinear material response, establishing a basis for the development of corresponding nonlinear material models.}},
  author       = {{Friesen, Olga and Claes, Leander and Hölscher, Jonas and Henning, Bernd and Scheidemann, Claus and Hemsel, Tobias and Kuess, Raphael and Walther, Andrea and Spieker, Carsten and Förstner, Jens}},
  issn         = {{0171-8096}},
  journal      = {{tm - Technisches Messen}},
  keywords     = {{tet_topic_piezo}},
  publisher    = {{Walter de Gruyter GmbH}},
  title        = {{{Measurement of multiphysical material parameters of piezoceramic components for high-power ultrasonic applications}}},
  doi          = {{10.1515/teme-2026-0042}},
  year         = {{2026}},
}

@inproceedings{66604,
  author       = {{Friesen, Olga and Hölscher, Jonas and Spieker, Carsten and Förstner, Jens and Claes, Leander}},
  location     = {{München}},
  title        = {{{Quantitative Modelling of Dynamic Nonlinearity in Piezoelectric Components}}},
  year         = {{2026}},
}

@inproceedings{62300,
  author       = {{Claes, Leander and Hölscher, Jonas and Friesen, Olga and Scheidemann, Claus and Hemsel, Tobias and Henning, Bernd}},
  booktitle    = {{2025 International Congress on Ultrasonics}},
  pages        = {{142–145}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{Estimation of third order elastic constants of piezoceramics using DC biased impedance measurements}}},
  doi          = {{10.5162/ultrasonic2025/a18-a6}},
  year         = {{2025}},
}

@article{62000,
  author       = {{Claes, Leander and Koch, Kevin and Friesen, Olga and Meihost, Lars}},
  issn         = {{2681-4617}},
  journal      = {{Acta Acustica}},
  number       = {{65}},
  publisher    = {{EDP Sciences}},
  title        = {{{Machine Learning-Supported Inverse Measurement Procedure for Broadband, Temperature Dependent Piezoelectric Material Parameters}}},
  doi          = {{10.1051/aacus/2025044}},
  volume       = {{9}},
  year         = {{2025}},
}

@inproceedings{62299,
  author       = {{Friesen, Olga and Scheidemann, Claus and Claes, Leander and Hemsel, Tobias and Henning, Bernd}},
  booktitle    = {{2025 International Congress on Ultrasonics}},
  pages        = {{138–141}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{Sensitivity Analysis and Material Parameter Estimation of a Pre-Stressed Langevin Transducer}}},
  doi          = {{10.5162/ultrasonic2025/a18-a4}},
  year         = {{2025}},
}

@inproceedings{62298,
  author       = {{Kuess, Raphael and Friesen, Olga and Henning, Bernd and Walther, Andrea}},
  booktitle    = {{2025 International Congress on Ultrasonics}},
  pages        = {{134–137}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{Identification of temperature-dependent material parameter functions in piezoelectricity}}},
  doi          = {{10.5162/ultrasonic2025/a18-a3}},
  year         = {{2025}},
}

@inproceedings{59689,
  author       = {{Friesen, Olga and Meihost, Lars and Koch, Kevin and Claes, Leander and Henning, Bernd}},
  location     = {{Copenhagen}},
  title        = {{{Estimation of piezoelectric material parameters under varying electric field conditions}}},
  doi          = {{10.71568/DASDAGA2025.078}},
  year         = {{2025}},
}

@inproceedings{62297,
  author       = {{Hölscher, Jonas and Friesen, Olga and Claes, Leander and Spieker, Carsten and Förstner, Jens and Henning, Bernd}},
  booktitle    = {{2025 International Congress on Ultrasonics}},
  keywords     = {{tet_topic_piezo}},
  pages        = {{130–133}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{Multiscale thermo-piezoelectric simulations using the finite element method}}},
  doi          = {{10.5162/ultrasonic2025/a18-a2}},
  year         = {{2025}},
}

@inproceedings{56834,
  author       = {{Friesen, Olga and Claes, Leander and Scheidemann, Claus and Feldmann, Nadine and Hemsel, Tobias and Henning, Bernd}},
  booktitle    = {{2023 International Congress on Ultrasonics, Beijing, China}},
  issn         = {{1742-6596}},
  pages        = {{012125}},
  publisher    = {{IOP Publishing}},
  title        = {{{Estimation of temperature-dependent piezoelectric material parameters using ring-shaped specimens}}},
  doi          = {{10.1088/1742-6596/2822/1/012125}},
  volume       = {{2822}},
  year         = {{2024}},
}

@misc{55470,
  author       = {{Koch, Kevin and Friesen, Olga and Claes, Leander}},
  publisher    = {{Zenodo}},
  title        = {{{Randomised material parameter impedance dataset of piezoelectric rings}}},
  doi          = {{10.5281/zenodo.13143680}},
  year         = {{2024}},
}

@misc{55416,
  author       = {{Claes, Leander and Koch, Kevin and Friesen, Olga and Meihost, Lars}},
  title        = {{{Machine learning in inverse measurement problems: An application to piezoelectric material characterisation}}},
  year         = {{2024}},
}

@article{56777,
  abstract     = {{The estimation of accurate piezoelectric material parameters is a fundamental prerequisite for simulation-driven design of piezoelectric actuators and sensors. Previous studies show that a full set of material parameters can be determined in an inverse procedure using a single disc-shaped specimen with an electrode structured for increased sensitivity with respect to all material parameters. However, in the case of high-power actuator applications, ring-shaped piezoelectric components are often employed, necessitating an adaptation of the previously developed method. The alteration in geometry introduces some advantages. Accordingly, there is no longer any requirement to modify the electrode structure in order to enhance sensitivity. The method to estimate the material parameters presented here consists of a total of three stages. An initial, approximate estimation of the material parameters is determined using analytical approximations for the resonance frequencies from the IEEE standard. These values are optimised in an inverse procedure that employs analytic expressions for the electrical impedance of piezoelectric rings as the forward model. Further refinement is achieved by using Finite Element (FE) simulations as the forward model again in an inverse procedure. The method is applied to electrical impedance measurement data, yielding material parameters for hard piezoelectric rings. The result shows a good agreement between the simulation and measurement results, indicating realistic material parameter values.}},
  author       = {{Friesen, Olga and Claes, Leander and Feldmann, Nadine and Henning, Bernd}},
  issn         = {{2196-7113}},
  journal      = {{tm - Technisches Messen}},
  publisher    = {{De Gruyter}},
  title        = {{{Estimation of piezoelectric material parameters of ring-shaped specimens}}},
  doi          = {{https://doi.org/10.1515/teme-2024-0107}},
  year         = {{2024}},
}

@inproceedings{53822,
  abstract     = {{Piezoelektrische Keramiken finden sowohl in Sensoren als auch in Aktoren Anwendung. Bei Hochleistungs-Ultraschallanwendungen sind diese Komponenten erheblichen elektrischen und mechanischen Belastungen ausgesetzt, was zum Auftreten nichtlinearer Effekte führt. Um das nichtlineare Materialverhalten piezoelektrischer Keramiken zu charakterisieren, kann eine statische mechanische Last aufgebracht werden, die den mechanischen Arbeitspunkt verschiebt. Durch Variation dieser statischen mechanischen Belastung kann das lineare Verhalten in jedem Betriebspunkt charakterisiert werden, woraufhin die nichtlinearen Eigenschaften des Materials angenähert werden können. Allerdings ist die Sicherstellung einer homogenen mechanischen Last anspruchsvoll. Alternativ kann eine hydrostatische Belastung realisiert werden, indem die Probe in einen Behälter gegeben wird, der mit unter Druck stehendem Fluid gefüllt ist. Dadurch wird eine gleichmäßige Lastverteilung über die Oberfläche der Probe erreicht.

In diesem Beitrag wird ein Versuchsaufbau zur Durchführung elektrischer Impedanzmessungen an piezoelektrischen Keramiken in einem Druckbehälter vorgestellt. Die Probe wird im Inneren des Druckbehälters elektrisch kontaktiert. Unter Verwendung von unter Druck stehendem Argon wird auf diese Weise die Messung der elektrischen Impedanz unter hydrostatischer Last von bis zu 200 bar ermöglicht. Anschließend wird ein inverses Verfahren angewendet, um die Materialparameter in Abhängigkeit von der aufgebrachten Last zu ermitteln.}},
  author       = {{Friesen, Olga and Pasha, Muhammad Ahsan and Schwengelbeck, Max and Claes, Leander and Baumhögger, Elmar and Henning, Bernd}},
  booktitle    = {{Fortschritte der Akustik - DAGA 2024}},
  location     = {{Hannover}},
  pages        = {{1117–1120}},
  title        = {{{Untersuchung piezoelektrischer Materialeigenschaften unter hydrostatischer Last}}},
  year         = {{2024}},
}

@inproceedings{43233,
  author       = {{Zeipert, Henning and von Germeten, Christian and Friesen, Olga and Claes, Leander and Johannesmann, Sarah and Henning, Bernd}},
  booktitle    = {{Fortschritte der Akustik - DAGA 2023}},
  location     = {{Hamburg}},
  pages        = {{819--822}},
  title        = {{{Investigation of change in dispersive behaviour during adhesive curing in multi-layered structures}}},
  year         = {{2023}},
}

@inproceedings{51117,
  author       = {{Scheidemann, Claus and Hemsel, Tobias and Friesen, Olga and Claes, Leander and Sextro, Walter}},
  location     = {{Jeju, Korea}},
  title        = {{{Influence of Temperature and Pre-Stress on the Piezoelectric Material Behavior of Ring-Shaped Ceramics}}},
  year         = {{2023}},
}

@misc{6558,
  author       = {{Friesen, Olga and Claes, Leander and Feldmann, Nadine and Henning, Bernd}},
  title        = {{{Estimation of piezoelectric material parameters of ring-shaped specimens}}},
  year         = {{2022}},
}