@article{63800,
  abstract     = {{In this contribution, we address the estimation of the frequency-dependent elastic parameters of polymers in the ultrasound range, which is formulated as an inverse problem. This inverse problem is implemented as a nonlinear regression-type optimization problem, in which the simulation signals are fitted to the measurement signals. These signals consist of displacement responses in waveguides, focusing on hollow cylindrical geometries to enhance the simulation efficiency. To accelerate the optimization and reduce the number of model evaluations and wait times, we propose two novel methods. First, we introduce an adaptation of the Levenberg–Marquardt method derived from a geometrical interpretation of the least-squares optimization problem. Second, we introduce an improved objective function based on the autocorrelated envelopes of the measurement and simulation signals. Given that this study primarily relies on simulation data to quantify optimization convergence, we aggregate the expected ranges of realistic material parameters and derive their distributions to ensure the reproducibility of optimizations with proper measurements. We demonstrate the effectiveness of our objective function modification and step adaptation for various materials with isotropic material symmetry by comparing them with the Broyden–Fletcher–Goldfarb–Shanno method. In all cases, our method reduces the total number of model evaluations, thereby shortening the time to identify the material parameters.}},
  author       = {{Itner, Dominik and Dreiling, Dmitrij and Gravenkamp, Hauke and Henning, Bernd and Birk, Carolin}},
  issn         = {{0888-3270}},
  journal      = {{Mechanical Systems and Signal Processing}},
  keywords     = {{Material parameter estimation, Waveguide, Nonlinear optimization, Inverse problem, Least squares}},
  pages        = {{113904}},
  title        = {{{A modified Levenberg–Marquardt method for estimating the elastic material parameters of polymer waveguides using residuals between autocorrelated frequency responses}}},
  doi          = {{https://doi.org/10.1016/j.ymssp.2026.113904}},
  volume       = {{247}},
  year         = {{2026}},
}

@techreport{65426,
  abstract     = {{In diesem Forschungsprojekt wurde ein Messverfahren zur Bestimmung akustischer Materialparameter von Polymeren im Ultraschallfrequenzbereich entwickelt. Das Verfahrens sollte, die üblichen standardisierten Prüfmethoden erweitern, die bislang primär im quasistatischen oder niederfrequenten Bereich eingesetzt wurden. Im Gegensatz zu bestehenden Verfahren wie dem Zeitstandversuch oder der Dynamisch Mechanischen Analyse (DMA) nach [DIN6721] sollte die neue Methode eine nicht-invasive Charakterisierung der (visko-)elastischen Materialparameter im Frequenzbereich von 0,75 MHz bis 2,5 MHz ermöglichen. Das entwickelte Ultraschallmesssystem arbeitet nach dem Puls Echo-Prinzip und kann eine räumlich segmentierte, ringförmige Anregung erzeugen. Die Bestimmung der frequenzabhängigen Materialparameter geschieht hierbei über ein inverses Verfahren. Die Ergebnisse des Projekts zeigen, dass die Segmentierung der Anregung, die Geometrie der Probe sowie das Puls-Echo-Messprinzip die Messergebnisse sowie die Sensitivität gegenüber Scherparametern wesentlich beeinflussen. Im Rahmen des Projektes wurde auch eine statistische Auswertung des Optimierungsverfahrens hinsichtlich transversal-isotroper Materialsymmetrie mit Rayleigh-Dämpfung durchgeführt. Die Ergebnisse zeigen, dass das entwickelte Verfahren gute Konvergenzeigenschaften aufweist und sich durch verbesserte Robustheit auszeichnet.}},
  author       = {{Dreiling, Dmitrij and Itner, Dominik and Birk, Carolin and Gravenkamp, Hauke and Henning, Bernd}},
  keywords     = {{Materialcharakterisierung, Polymer, Inverses Problem, Ultraschall, Optimierung}},
  pages        = {{12}},
  publisher    = {{Hannover : Technische Informationsbibliothek}},
  title        = {{{Vollständige Bestimmung der akustischen Materialparameter von Polymeren II}}},
  doi          = {{https://doi.org/10.34657/33602}},
  year         = {{2026}},
}

@article{59995,
  abstract     = {{<jats:title>Abstract</jats:title>
               <jats:p>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.</jats:p>}},
  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{62301,
  author       = {{Dreiling, Dmitrij and Itner, Dominik and Gravenkamp, Hauke and Birk, Carolin and Henning, Bernd}},
  booktitle    = {{2025 International Congress on Ultrasonics}},
  pages        = {{102–105}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{A Measurement Setup for the Determination of Temperature-Dependent Viscoelastic Material Parameters Using an Ultrasonic Pulse-Echo Technique}}},
  doi          = {{10.5162/ultrasonic2025/a12-c5}},
  year         = {{2025}},
}

@article{55519,
  abstract     = {{Im Folgenden wird ein wellenleiterbasierter Ansatz zur Bestimmung von viskoelastischen Materialparametern für eine numerische Simulation der Schallausbreitung in transversal isotropen Polymeren vorgestellt. Ein hierfür entwickeltes Puls-Echo-Messverfahren liefert Messsignale, welche anschließend zur Schätzung der Materialparameter von absorbierenden, zylindrischen Polymerproben genutzt werden. Darüber hinaus kommen in dem Messaufbau Schallwandler zum Einsatz, die eine segmentierte ringförmige Anregung der Probe verursachen und die Sensitivität gegenüber Scherbewegungen erhöhen. Mithilfe einer ersten strahlentheoretischen Startwertschätzung werden eine multimodale, semianalytische Simulation der Schallausbreitung im Wellenleiter realisiert und schließlich die Materialparameter im inversen Ansatz geschätzt.}},
  author       = {{Dreiling, Dmitrij and Itner, Dominik and Gravenkamp, Hauke and Birk, Carolin and Henning, Bernd}},
  isbn         = {{2196-7113}},
  journal      = {{tm - Technisches Messen}},
  keywords     = {{Materialcharakterisierung, Puls-Echo Methode, inverse Verfahren}},
  number       = {{s1}},
  pages        = {{26--31}},
  publisher    = {{De Gruyter}},
  title        = {{{Die Bestimmung viskoelastischer Materialparameter von Polymeren mittels eines Puls-Echo-Messverfahrens}}},
  doi          = {{10.1515/teme-2024-0045}},
  volume       = {{91}},
  year         = {{2024}},
}

@inproceedings{56835,
  author       = {{Dreiling, Dmitrij and Itner, Dominik and Hetkämper, Tim and Birk, Carolin and Gravenkamp, Hauke and Henning, Bernd}},
  booktitle    = {{2023 International Congress on Ultrasonics, Beijing, China}},
  issn         = {{1742-6596}},
  pages        = {{012169}},
  publisher    = {{IOP Publishing}},
  title        = {{{A pulse-echo measurement setup to determine viscoelastic material parameters}}},
  doi          = {{10.1088/1742-6596/2822/1/012169}},
  volume       = {{2822}},
  year         = {{2024}},
}

@inproceedings{45205,
  author       = {{Dreiling, Dmitrij and Itner, Dominik and Hetkämper, Tim and Birk, Carolin and Gravenkamp, Hauke and Henning, Bernd}},
  booktitle    = {{SMSI 2023 Conference}},
  isbn         = {{978-3-9819376-8-8}},
  location     = {{Nürnberg}},
  pages        = {{394 -- 395}},
  publisher    = {{AMA Association For Sensors And Measurement}},
  title        = {{{Improved determination of viscoelastic material parameters using a pulse-echo measurement setup}}},
  doi          = {{10.5162/SMSI2023/P59}},
  year         = {{2023}},
}

@misc{17090,
  author       = {{Itner, Dominik and Gravenkamp, Hauke and Dreiling, Dmitrij and Birk, Carolin and Henning, Bernd}},
  publisher    = {{International Association for Computational Mechanics (IACM)}},
  title        = {{{Differentiation of an SBFE model in the context of material parameter determination}}},
  year         = {{2022}},
}

@article{21082,
  author       = {{Itner, Dominik and Gravenkamp, Hauke and Dreiling, Dmitrij and Feldmann, Nadine and Henning, Bernd}},
  issn         = {{1617-7061}},
  journal      = {{PAMM}},
  title        = {{{Simulation of guided waves in cylinders subject to arbitrary boundary conditions for applications in material characterization}}},
  doi          = {{10.1002/pamm.202000232}},
  year         = {{2021}},
}

@misc{21564,
  author       = {{Itner, Dominik and Gravenkamp, Hauke and Dreiling, Dmitrij and Feldmann, Nadine and Henning, Bernd}},
  title        = {{{On the forward simulation and cost functions for the ultrasonic material characterization of polymers }}},
  year         = {{2021}},
}

@inproceedings{25880,
  author       = {{Hetkämper, Tim and Dreiling, Dmitrij and Claes, Leander and Henning, Bernd}},
  booktitle    = {{Fortschritte der Akustik - DAGA 2021}},
  title        = {{{Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik}}},
  year         = {{2021}},
}

@inproceedings{25265,
  abstract     = {{Waveguide-based methods can be used for the non-destructive determination of acoustic material parameters. One of these methods is based on transmission measurements of cylindrical polymeric specimens. Here, the experimental setup consists of two transducers, which excite and receive the waveguide modes at the faces of the cylinder. The measurement, as well as a forward model, are used to determine material parameters of the polymeric specimen in an inverse approach.
1-3 piezoelectric composites are used as an active element because they can be approximated by a thickness vibration only. This allows an easy identification of Mason model parameters to characterise the transducers’ vibration behaviour. 
However, sensitivity analysis shows a high uncertainty in the determination of the mechanical shear parameters due to the uniform excitation. To increase the sensitivity to these shear motions, arbitrary excitations were investigated by means of numerical simulation. 
In order to be able to realise the determined optimal excitation, new transducer prototypes were designed. By subdividing the electrodes of the active element, for example, ring-shaped excitation is feasible. Furthermore, it can be shown that modelling these transducers with a one-dimensional Mason model is sufficient.}},
  author       = {{Dreiling, Dmitrij and Itner, Dominik and Feldmann, Nadine and Scheidemann, Claus and Gravenkamp, Hauke and Henning, Bernd}},
  booktitle    = {{Fortschritte der Akustik - DAGA 2021}},
  location     = {{Wien}},
  publisher    = {{Deutsche Gesellschaft für Akustik e.V. (DEGA)}},
  title        = {{{Application and modelling of ultrasonic transducers using 1-3 piezoelectric composites with structured electrodes}}},
  year         = {{2021}},
}

@inproceedings{40541,
  author       = {{Itner, D. and Gravenkamp, H. and Dreiling, Dmitrij and Feldmann, Nadine and Henning, Bernd}},
  booktitle    = {{14th WCCM-ECCOMAS Congress}},
  publisher    = {{CIMNE}},
  title        = {{{Simulation of Guided Waves in Cylinders Subject to Arbitrary Boundary Conditions Using the Scaled Boundary Finite Element Method}}},
  doi          = {{10.23967/wccm-eccomas.2020.307}},
  volume       = {{700}},
  year         = {{2021}},
}

@article{21232,
  author       = {{Itner, Dominik and Gravenkamp, Hauke and Dreiling, Dmitrij and Feldmann, Nadine and Henning, Bernd}},
  issn         = {{0041-624X}},
  journal      = {{Ultrasonics}},
  title        = {{{Efficient semi-analytical simulation of elastic guided waves in cylinders subject to arbitrary non-symmetric loads}}},
  doi          = {{10.1016/j.ultras.2021.106389}},
  year         = {{2021}},
}

@inproceedings{17089,
  author       = {{Dreiling, Dmitrij and Itner, Dominik Thor and Feldmann, Nadine and Gravenkamp, Hauke and Henning, Bernd}},
  location     = {{Nürnberg}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{Increasing the sensitivity in the determination of material parameters by using arbitrary loads in ultrasonic transmission measurements}}},
  doi          = {{10.5162/SMSI2020/D1.3}},
  year         = {{2020}},
}

@inproceedings{19502,
  author       = {{Hetkämper, Tim and Krumme, Matthias and Dreiling, Dmitrij and Claes, Leander}},
  booktitle    = {{SEFI 48th Annual Conference Proceedings - Engaging Engineering Education}},
  location     = {{Enschede}},
  pages        = {{1309--1313}},
  publisher    = {{SEFI}},
  title        = {{{A modular, scalable open-hardware platform for project-based laboratory courses in electrical engineering studies}}},
  year         = {{2020}},
}

@inproceedings{12952,
  author       = {{Dreiling, Dmitrij and Feldmann, Nadine and Henning, Bernd}},
  keywords     = {{piezoelectric materials, piezoelectric properties, DC bias field, non-linear material parameters}},
  location     = {{Nürnberg}},
  publisher    = {{AMA Service GmbH}},
  title        = {{{A DC bias approach to the characterisation of non-linear material parameters of piezoelectric ceramics}}},
  doi          = {{10.5162/sensoren2019/5.1.2}},
  year         = {{2019}},
}