Prof. Dr. Bernd Henning - Kontakt (Universität Paderborn)

Schlieren imaging with fractional Fourier transform to visualise ultrasonic fields

T. Hetkämper, L. Claes, B. Henning, in: ITG-Fachbericht 303 - Sensoren und Messsysteme - Beiträge der 21. ITG/GMA-Fachtagung, 2022

Estimation of viscoelastic material parameters of polymers using Lamb waves

S. Johannesmann, L. Claes, B. Henning, in: Fortschritte der Akustik - DAGA 2022, 2022, pp. 1401-1404

Quantification of the adhesive coupling of layered structures using guided ultrasonic waves

M. Nicolai, H. Zeipert, Y. Lugovtsova, J. Bulling, S. Johannesmann, J. Prager, B. Henning, in: Fortschritte der Akustik - DAGA 2022, 2022, pp. 1394-1397

Identification of piezoelectric material parameters using optimised multi-electrode specimens

L. Claes, N. Feldmann, V. Schulze, B. Jurgelucks, A. Walther, B. Henning, in: Fortschritte der Akustik - DAGA 2022, 2022, pp. 1326-1329

Lamb wave based approach to the determination of acoustic material parameters

S. Johannesmann, L. Claes, N. Feldmann, H. Zeipert, B. Henning, tm - Technisches Messen (2022), 89(7 - 8), pp. 493 - 506

Abstract

DOI

<jats:title>Abstract</jats:title> <jats:p>In this paper a measurement procedure to identify viscoelastic material parameters of plate-like samples using broadband ultrasonic waves is presented. Ultrasonic Lamb waves are excited via the thermoelastic effect using laser radiation and detected by a piezoelectric transducer. The resulting measurement data is transformed to yield information about multiple propagating Lamb waves as well as their attenuation. These results are compared to simulation results in an inverse procedure to identify the parameters of an elastic and a viscoelastic material model.</jats:p>

Quantifying the coupling strength of adhesively bonded materials by investigating mode repulsion regions

H. Zeipert, S. Johannesmann, M. Nicolai, Y. Lugovtsova, J. Prager, B. Henning, in: Fortschritte der Akustik - DAGA 2021, 2021

К ОПРЕДЕЛЕНИЮ ПРОЧНОСТИ КЛЕЕВОГО СОЕДИНЕНИЯ В МНОГОСЛОЙНЫХ МАТЕРИАЛАХ ПУТЕМ ИССЛЕДОВАНИЯ ОБЛАСТЕЙ РАСТАЛКИВАНИЯ БЕГУЩИХ УПРУГИХ ВОЛН

Y. Lugovtsova, H. Zeipert, S. Johannesmann, M. Nicolai, J. Prager, B. Henning, in: МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ В ЕСТЕСТВЕННЫХ НАУКАХ - XXX Всероссийская школа-конференция, 2021

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Paper - Mode Repulsion - 2021 MMEN (Perm).pdf -

Investigating peculiarities of piezoelectric detection methods for acoustic plate waves in material characterisation applications

L. Claes, H. Schmiegel, C. Grünsteidl, S. Johannesmann, M. Webersen, B. Henning, tm - Technisches Messen (2021), 88(3), pp. 147-155

Abstract

DOI

Acoustic waves in plates have proven a viable tool for testing and material characterisation purposes. There are a multitude of options for excitation and detection of theses waves, such as optical and piezoelectric systems. While optical systems, with thermoelastic excitation and interferometric detection, have the benefit of being contactless, they usually require rather complex and expensive experimental setups. Piezoelectric systems are more easily realised but require direct contact with the specimen and usually have a limited bandwidth, especially in case of piezoelectric excitation. In this work, the authors compare the properties of piezoelectric and optical detection methods for broad-band acoustic signals. The shape (e. g. the displacement) of a propagating plate wave is given by its frequency and wave number, allowing to investigate correlations between mode shapes and received signal strengths. This is aided by evaluations in normalised frequency and wavenumber space, facilitating comparisons of different specimens. Further, the authors explore possibilities to utilise the specific properties of the detection methods to determine acoustic material parameters.

Simulation of guided waves in cylinders subject to arbitrary boundary conditions for applications in material characterization

D. Itner, H. Gravenkamp, D. Dreiling, N. Feldmann, B. Henning, PAMM (2021)

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Efficient semi-analytical simulation of elastic guided waves in cylinders subject to arbitrary non-symmetric loads

D. Itner, H. Gravenkamp, D. Dreiling, N. Feldmann, B. Henning, Ultrasonics (2021), 106389

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On the forward simulation and cost functions for the ultrasonic material characterization of polymers

D. Itner, H. Gravenkamp, D. Dreiling, N. Feldmann, B. Henning, 2021

Lamb wave based approach to the determination of elastic and viscoelastic material parameters

S. Johannesmann, L. Claes, B. Henning, tm - Technisches Messen (2021), 88(s1), pp. s28-s33

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Measurement and Simulation of Lamb Waves in Adhesive-bonded Multilayer Systems

H. Zeipert, L. Claes, S. Johannesmann, M. Webersen, Y. Lugovtsova, J. Prager, B. Henning, 2021, pp. 91 - 92

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An approach to adhesive bond characterisation using guided acoustic waves in multi-layered plates

H. Zeipert, L. Claes, S. Johannesmann, Y. Lugovtsova, M. Nicolai, J. Prager, B. Henning, at - Automatisierungstechnik (2021), pp. 962-969

Abstract

DOI

An approach for the non-destructive characterisation of adhesive bonds using guided ultrasonic waves is presented. Pulsed laser radiation is used to thermoacoustically excite broadband ultrasonic waves in a multi-layered sample, consisting of a metal plate adhesively joined to a polymeric layer using synthetic resin. The resulting signals are received by a purpose-built piezoelectric transducer. Varying the distance between excitation and detection yields spatio-temporal measurement data, from which the dispersive properties of the propagating waves can be inferred using a two-dimensional Fourier transform, assuming the plates to act as coupled waveguides. Coupled multi-layered waveguides show an effect referred to as <jats:italic>mode repulsion</jats:italic>, where the distance between certain modes in the frequency-wavenumber domain is assumed to be a measure of coupling strength. Measurements at different stages of curing of the adhesive layer are performed and evaluated. A comparison of the results shows changes in the dispersive properties, namely an increased modal bandwidth for the fully cured sample as well as an increased modal distance.

Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik

T. Hetkämper, D. Dreiling, L. Claes, B. Henning, in: Fortschritte der Akustik - DAGA 2021, 2021

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Tomographie des Schallfelds von Ultraschallwandlern mittels Schlierentechnik.pdf -

Measurement procedure for acoustic absorption and bulk viscosity of liquids

L. Claes, R.S. Chatwell, E. Baumhögger, T. Hetkämper, H. Zeipert, J. Vrabec, B. Henning, Measurement (2021), 109919

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Application and modelling of ultrasonic transducers using 1-3 piezoelectric composites with structured electrodes

D. Dreiling, D. Itner, N. Feldmann, C. Scheidemann, H. Gravenkamp, B. Henning, in: Fortschritte der Akustik - DAGA 2021, Deutsche Gesellschaft für Akustik e.V. (DEGA), 2021

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.

Modelling damping in piezoceramics: A comparative study

N. Feldmann, V. Schulze, L. Claes, B. Jurgelucks, L. Meihost, A. Walther, B. Henning, tm - Technisches Messen (2021), 88(5), pp. 294 - 302

Abstract

DOI

The progress in numerical methods and simulation tools promotes the use of inverse problems in material characterisation problems. A newly developed procedure can be used to identify the behaviour of piezoceramic discs over a wide frequency range using a single specimen via fitting simulated and measured impedances by optimising the underlying material parameters. Since there is no generally accepted damping model for piezoelectric ceramics, several mechanical damping models are examined for the material identification. Three models have been chosen and their ability to replicate the measured impedances is evaluated. On the one hand, the common Rayleigh model is considered as a reference. On the other hand, a Zener model and a model using complex constants are extended to model the transversely isotropic material. As the Rayleigh model is only valid for a limited frequency range, it fails to model the broadband behaviour of the material. The model using complex constants leads to the best fit over a wide frequency range while at the same time only adding three additional parameters for modelling damping. Thus, damping can be assumed approximately frequency-independent in piezoceramics.

Optimised Multi-Electrode Topology for Piezoelectric Material Characterisation

L. Claes, N. Feldmann, B. Jurgelucks, V. Schulze, S. Schmidt, A. Walther, B. Henning, 2021, pp. 237-238

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The Influence of Hydrothermal Aging on the Material Properties of Continuous Fiber-Reinforced Thermoplastics and its Non-Destructive Characterization

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, in: Advances in Polymer Processing 2020, 2020

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The Influence of Hydrothermal Aging on the Material Properties of Continuous Fiber-Reinforced Thermoplastics and its Non-Destructive Characterization

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, in: Advances in Polymer Processing 2020, Springer, 2020

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Recombination mechanisms of luminescence type gas sensors

M. Poeplau, S. Ester, B. Henning, T. Wagner, Physical Chemistry Chemical Physics (2020)

Abstract

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<p>The impact of the recombination mechanisms in luminescent materials is discussed with regard to luminescence based gas-sensing applications and the use of semiconducting materials, as an alternative to organic–metal complexes, is outlined.</p>

Increasing the sensitivity in the determination of material parameters by using arbitrary loads in ultrasonic transmission measurements

D. Dreiling, D.T. Itner, N. Feldmann, H. Gravenkamp, B. Henning, AMA Service GmbH, 2020

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DOI

https://www.ama-science.org/proceedings/getFile/Zmp0ZN==

Estimation of acoustic wave non-linearity in ultrasonic measurement systems

L. Claes, C. Steidl, T. Hetkämper, B. Henning, arXiv.org (2020)

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arXiv

https://arxiv.org/pdf/2001.05708

Reduction of systematic measurement deviation in acoustic absorption measurement systems

L. Claes, E. Baumhögger, T. Rüther, J. Gierse, T. Tröster, B. Henning, in: Fortschritte der Akustik - DAGA 2020, 2020, pp. 1077-1080

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daga.pdf -

Solving piezoelectric inverse problems using Algorithmic Differentiation

N. Feldmann, V. Schulze, B. Jurgelucks, B. Henning, in: Fortschritte der Akustik - DAGA 2020, 2020, pp. 1125-1128

Determination of Murnaghan constants of plate-shaped polymers under uniaxial tensile load

S. Johannesmann, S. Becker, M. Webersen, B. Henning, in: SMSI 2020 - Measurement Science, 2020

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Inverse piezoelectric material parameter characterization using a single disc-shaped specimen

N. Feldmann, V. Schulze, L. Claes, B. Jurgelucks, A. Walther, B. Henning, tm - Technisches Messen (2020), pp. 50-55

Abstract

DOI

The increasingly simulation-driven design process of ultrasonic transducers requires several reliable parameters for the description of the material behaviour. Exact results can only be achieved when a single specimen is used in the identification process, which typically is prone to the problem of low sensitivities to certain material parameters and thus high uncertainties. Therefore, a custom electrode topology for increased sensitivity is proposed for a piezoceramic disc. The thereupon conducted measurements of the electric impedance can be used as a starting point for an inverse approach where an equivalent simulation model is used to identify fitting material parameters. An optimisation strategy based on a preliminary sensitivity analysis is presented that leads to a good agreement between measurement and simulation. Furthermore, the proposed measurement procedure is able to evaluate the quality of the simulation model. Hence, different frequency-dependent damping models are presented and evaluated.

Characterization of the linear-acoustic material behavior of fiber-reinforced composites using lamb waves

S. Johannesmann, M. Webersen, J. Düchting, L. Claes, B. Henning, in: 45th Annual Review of Progress in Quantitative Nondestructive Evaluation , 2019

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P2.9 Comparison of deep feature extraction techniques for varying-length time series from an industrial piercing press

C. Thiel, C. Steidl, B. Henning, in: 20. GMA/ITG-Fachtagung. Sensoren und Messsysteme 2019, 2019

Abstract

DOI

The continuous refinement of sensor technologies enables the manufacturing industry to capture increasing amounts of data during the production process. As processes take time to complete, sensors register large amounts of time-series-like data for each product. In order to make this data usable, a feature extraction is mandatory. In this work, we discuss and evaluate different network architectures, input pre-processing and cost functions regarding, among other aspects, their suitability for time series of different lengths.

A sensitivity-based optimisation procedure for the characterisation of piezoelectric discs

N. Feldmann, B. Jurgelucks, L. Claes, B. Henning, in: 2019 International Congress on Ultrasonics, 2019

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Analysis of Lamb wave mode repulsion and its implications to the characterisation of adhesive bonding strength

Y. Lugovtsova, S. Johannesmann, B. Henning, J. Prager, in: 2019 International Congress on Ultrasonics, Acoustical Society of America, 2019

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Evolutionary algorithm for the design of passive electric matching networks for ultrasonic transducers

T. Hetkämper, L. Claes, B. Henning, in: 2019 International Congress on Ultrasonics, 2019

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Acoustic absorption measurement for the determination of the volume viscosity of pure fluids / Messverfahren für die akustischen Absorption zur Bestimmung der Volumenviskosität reiner Fluide

L. Claes, L.M. Hülskämper, E. Baumhögger, N. Feldmann, R.S. Chatwell, J. Vrabec, B. Henning, tm - Technisches Messen (2019), pp. 2-6

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Störeffektunterdrückung in 2D-Messdaten mittels DiscoGAN

S. Johannesmann, D. Springer, C. Thiel, B. Henning, in: Fortschritte der Akustik - DAGA 2019, Deutsche Gesellschaft für Akustik, 2019, pp. 1055-1058

Akustische Charakterisierung der mechanischen Eigenschaften künstlich gealterter Polymere

M. Webersen, M. Hüttner, F. Woitschek, E. Moritzer, B. Henning, in: Fortschritte der Akustik - DAGA 2019, 2019

Quantification of frequency-dependent absorption phenomena

L. Claes, S. Johannesmann, E. Baumhögger, B. Henning, in: 2019 International Congress on Ultrasonics, 2019

DOI

A DC bias approach to the characterisation of non-linear material parameters of piezoelectric ceramics

D. Dreiling, N. Feldmann, B. Henning, AMA Service GmbH, 2019

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DOI

https://www.ama-science.org/proceedings/getFile/ZmDmAN

An inverse approach to the characterisation of material parameters of piezoelectric discs with triple-ring-electrodes

N. Feldmann, B. Jurgelucks, L. Claes, V. Schulze, B. Henning, A. Walther, tm - Technisches Messen (2018), 86(2), pp. 59-65

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An acoustic waveguide-based approach to the complete characterisation of linear elastic, orthotropic material behaviour

S. Johannesmann, J. Düchting, M. Webersen, L. Claes, B. Henning, tm - Technisches Messen (2018), 2018(85), pp. 478-486

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Acoustic material characterization of prestressed, plate-shaped specimens

S. Johannesmann, T. Brockschmidt, F. Rump, M. Webersen, L. Claes, B. Henning, in: Sensoren und Messsysteme, VDE Verlag GmbH, 2018, pp. 231-234

Optimization of triple-ring electrodes on piezoceramic transducers using algorithmic differentiation

B. Jurgelucks, L. Claes, A. Walther, B. Henning, Optimization Methods and Software (2018), pp. 1-21

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Guided ultrasonic waves for determining effective orthotropic material parameters of continuous-fiber reinforced thermoplastic plates

M. Webersen, S. Johannesmann, J. Düchting, L. Claes, B. Henning, Ultrasonics (2018), 84, pp. 53-62

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Akustische Charakterisierung der richtungsabhängigen elastischen Eigenschaften faserverstärkter Kunststoffe

M. Webersen, S. Johannesmann, J. Düchting, L. Claes, B. Henning, in: Fortschritte der Akustik - DAGA 2018, 2018, pp. 1263-1266

Efficient optimisation of initial values for characterising piezoelectric material parameters

N. Feldmann, B. Henning, in: Fortschritte der Akustik, 2018, pp. 1275-1278

Extraction of Interpretable Features from Temporal Measurements using Approximate Prototypes

C. Thiel, N. Feldmann, B. Henning, in: Sensoren und Messsysteme 2018, VDE Verlag GmbH, 2018, pp. 536-539

Materialparameter von bleihaltigen und bleifreien Piezokeramiken und ihre Bedeutung in der Anwendung

L. Claes, N. Feldmann, B. Henning, 2018

Additiv gefertigte, akustische Diffusor-Strukturen für Ultraschallanwendungen

L. Claes, H. Zeipert, P. Koppa, T. Tröster, B. Henning, 2018

Vollständige Charakterisierung von piezoelektrischen Scheiben mit Ringelektroden

N. Feldmann, B. Jurgelucks, L. Claes, B. Henning, 2018

Einfluss mechanischer Vorspannung auf das mechanische Materialverhalten von Polymeren

M. Webersen, S. Johannesmann, T. Brockschmidt, F. Rump, L. Claes, B. Henning, 2018

Viskoelastizität und Anisotropie von Kunststoffen: Ultraschallbasierte Methoden zur Materialparameterbestimmung

F. Bause, L. Claes, M. Webersen, S. Johannesmann, B. Henning, tm - Technisches Messen (2017), 84(3)

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A Spectral Approach to Acoustic Absorption Measurement

L. Claes, R.S. Chatwell, J. Vrabec, B. Henning, in: PROCEEDINGS -- AMA Conferences 2017, AMA Service GmbH, 2017, pp. 304-309

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Acoustic Material Characterization of Additively Manufactured Components

L. Claes, A. Jäger, S. Johannesmann, M. Webersen, M. Kupnik, B. Henning, in: PROCEEDINGS -- AMA Conferences 2017, AMA Service GmbH, 2017, pp. 605-610

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Additively manufactured acoustic diffuser structures for ultrasonic measurement applications

L. Claes, H. Zeipert, P. Koppa, T. Tröster, B. Henning, in: Proceedings of Meetings on Acoustics, 2017, pp. 030004

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Evaluating the Influence of 3D-Printing Parameters on Acoustic Material Properties

A. Jäger, S. Johannesmann, L. Claes, M. Webersen, B. Henning, M. Kupnik, in: 2017 IEEE IUS~Proceedings, 2017

Inverser Ansatz zur akustischen Charakterisierung plattenförmiger Materialproben

S. Johannesmann, L. Claes, M. Webersen, B. Henning, in: Fortschritte der Akustik - DAGA 2017, Deutsche Gesellschaft für Akustik e.V. 2017, 2017, pp. 999-1002

Material parameter determination of a piezoelectric disc with triple-ring-electrodes for increased sensitivity

B. Jurgelucks, N. Feldmann, L. Claes, B. Henning, A. Walther, in: Proceedings of Meetings on Acoustics, 2017, pp. 030010

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Ultrasonic measurements in the characterization of viscoelasticity and aging of polymers

F. Bause, L. Claes, M. Webersen, B. Henning, in: PROCEEDINGS -- AMA Conferences 2017, 2017, pp. 414

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Determining fractional Zener model parameters from low frequency DMA measurements

N. Feldmann, F. Bause, B. Henning, in: Proceedings – AMA Conferences 2017, 2017

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Spektrale Verfahren zur Bestimmung der akustischen Absorption in fluiden Medien

L. Claes, N. Feldmann, B. Henning, 2017

Ultraschallbasierte Charakterisierung des Alterungsverhaltens von Polymeren

M. Webersen, B. Henning, 2017

An Approach to Non-Destructive Testing of Aged Polymers

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, in: 32nd International Conference of the Polymer Processing Society (PPS), 2016

Detecting Molecular Damage - Non-Destructive Characterization of Molecular Changes in Aged Polymers

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, Kunststoffe international (2016)(10. Jg. Heft 4), pp. 43-45

Ein Ansatz zur zerstörungsfreien Prüfung von hydrothermisch gealterten Polymeren

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, in: Safe and Reliable Structures, 2016

Molekularen Schäden auf der Spur - Zerstörungsfreie Charakterisierung molekularer Veränderungen in gealterten Polymeren

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, Kunststoffe (2016)(106. Jg. Heft 6), pp. 94-96

Non-Destructive Characterization of Hygrothermally Aged Polymers

V. Schöppner, M. Hüttner, B. Henning, M. Webersen, in: 74th Annual Technical Conference of the Society of Plastics Engineers (ANTEC), 2016

The Development of a Non-Destructive Testing Method for the Characterization of Hygrothermally Aged Polymers

E. Moritzer, I. Fiebig, M. Hüttner, B. Henning, M. Webersen, in: 69th Annual Assembly of the International Institute of Welding (IIW), 2016

Ultraschallbasierte Charakterisierung von gealterten Polymeren

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, Jahresmagazin Kunststofftechnik (2016), pp. 98-103

Zerstörungsfreie Charakterisierung des hydrothermischen Alterungsverhaltens von Polymeren

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, in: 18. GMA/ITG Fachtagung Sensoren und Messsysteme, 2016

Ultrasonic transmission measurements in the characterization of viscoelasticity utilizing polymeric waveguides

F. Bause, J. Rautenberg, N. Feldmann, M. Webersen, L. Claes, H. Gravenkamp, B. Henning, Measurement Science and Technology (2016), 27(10)

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Determination of the material properties of polymers using laser-generated broadband ultrasound

L. Claes, T. Meyer, F. Bause, J. Rautenberg, B. Henning, Journal of Sensors and Sensor Systems (2016), 5(1), pp. 187-196

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DOI

https://www.j-sens-sens-syst.net/5/187/2016/jsss-5-187-2016.pdf

Characterization of Continuous-fiber Reinforced Thermoplastics Using Thermoacoustically Excited Ultrasonic Lamb Waves

M. Webersen, S. Johannesmann, L. Claes, B. Henning, in: 2016 IEEE IUS~Proceedings, 2016

Vergleich zweier Verfahren der Unsicherheitsabschätzung bei linearisierten inversen Problemen mittels Bayes’scher Inferenz und Pseudoinverse am Beispiel akustischer Transmissionsmessung

N. Feldmann, F. Bause, B. Henning, in: Sensoren und Messsysteme 2016, 2016

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Uncertainty estimation for linearised inverse problems comparing Bayesian inference and a pseudoinverse approach for acoustic transmission measurements

N. Feldmann, F. Bause, B. Henning, tm - Technisches Messen (2016), 84(4)

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GUM-konforme Unsicherheitsabschätzung bei inversen Problemen am Beispiel akustischer Transmissionsmessungen

N. Feldmann, F. Bause, B. Henning, 2016

Erweiterung des Raman-Nath-Modells zur Analyse von Schlierenabbildungen

S. Olfert, B. Henning, Technisches Messen (2016), 83(4), pp. 219-224

5.3.1 - Ein ultraschallbasiertes inverses Messverfahren zur Charakterisierung viskoelastischer Materialparameter von Polymeren

F. Bause, B. Henning, LibreCat University, 2016

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3.2.3 - Direktgravimetrischer Partikelmasse-Sensor zur quasikontinuierlichen Emissionsmessung

S. Ester, M. Struschka, B. Henning, LibreCat University, 2016

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An Approach to Non-Destructive Testing of Aged Polymers

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, 2016

Molekularen Schäden auf der Spur

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, Kunststoffe (2016)(4), pp. 94-96

Detecting Molecular Damage

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, Kunststoffe International (2016)(4), pp. 43-45

Non-destructive characterization of hygrothermally aged polymers

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, 2016

Ultraschallbasierte Charakterisierung von gealterten Polymeren

E. Moritzer, M. Hüttner, B. Henning, M. Webersen, in: Jahresmagazin Kunststofftechnik 2016, 2016, pp. 2-7

Zerstörungsfreie Charakterisierung des hydrothermischen Alterungsverhaltens von Polymeren

M. Webersen, M. Hüttner, F. Bause, E. Moritzer, B. Henning, 2016, pp. 683-688

Abstract

DOI

In der zerstörungsfreien Werkstoffprüfung sind bereits zahlreiche Verfahren etabliert, deren Ziel die Detektion makroskopischer Defekt- und Fehlstellen (z.B. Risse, Poren, Fremdeinschlüsse) ist. Insbesondere bei Polymerwerkstoffen muss jedoch auch die Materialalterung auf molekularer Ebene berücksichtigt werden, die sich (zumeist negativ) auf die Materialkenngrößen auswirkt. Gängige Verfahren zur Bestimmung dieser Kenngrößen arbeiten jedoch üblicherweise zerstörend und sind somit beispielsweise für die vorbeugende Instandhaltung oder die Online-Komponentenüberwachung nur eingeschränkt geeignet. In diesem Beitrag wird ein Verfahren zur zerstörungsfreien Charakterisierung des Alterungszustandes von Polymeren vorgestellt. Dazu wird der Zusammenhang zwischen akustisch (zerstörungsfrei, mittels Ultraschall-Transmissionsmessung) bestimmten Kenngrößen und klassisch (zerstörend, z.B. mittels Zugprüfung) bestimmten hydrothermischer Alterung auf das Material Polyamid 6 (PA6) untersucht. Die Ergebnisse Kenngrößen betrachtet. Exemplarisch werden die Auswirkungen zeigen einen engen Zusammenhang zwischen der zerstörend bestimmten Viskositätszahl, die ein Maß für die mittlere Molekülkettenlänge darstellt, und der akustischen Longitudinalwellengeschwindigkeit. Das Molekülkettenabbau (Depolymerisation) bestimmt ist, kann somit auch akustisch und zerstörungsfrei charakterisiert werden. Auf dieser Basis können neuartige, zerstörungsfrei arbeitende Messsysteme entwickelt werden.

Detection of ultrasonic plate waves using ceramic strip transducers

L. Claes, F. Bause, J. Rautenberg, B. Henning, in: Proceedings SENSOR 2015, 2015, pp. 775-779

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Analyse integral erfasster rotationssymmetrischer Schallwechseldruckverteilungen in Schlierenabbildungen

S. Olfert, B. Henning, 2015

Analyse integral erfasster Schallwechseldruckverteilungen in Schlierenabbildungen

S. Olfert, B. Henning, in: XXIX Messtechnisches Symposium, 2015

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Model based sensitivity analysis in the determination of viscoelastic material properties using transmission measurements through circular waveguides

F. Bause, H. Gravenkamp, J. Rautenberg, B. Henning, 2015, pp. 204-207

Abstract

Several ultrasonic approaches for material determination are formulated in terms of an (nonlinear) inverse problem, e.g. immersion technique (Castaings et al. (2000)) or plate-waveguide techniques (Marzani et al. (2012)). In this contribution we focus on cylindrical waveguides for ultrasonic material determination and especially on the sensitivity of recorded transmission signals to the material properties. We utilize composite scaled sensitivities to determine the information content that can be achieved by the setup to certain parameters and discuss the limitations of the approach.

Transient modeling of ultrasonic guided waves in circular viscoelastic waveguides for inverse material characterization

F. Bause, H. Gravenkamp, J. Rautenberg, B. Henning, Measurement Science and Technology (2015), 095602

DOI

Schallfeldcharakterisierung mittels Schlierentechnik

S. Olfert, B. Henning, DEGA and {Deutsche Gesellschaft f{\"u}r Akustik e.V}, 2015, pp. 1560-1561

Utilizing guided acoustic waves to measure dispersive material properties of polymers

J. Rautenberg, F. Bause, B. Henning, in: AMA~Conferences 2015, 2015, pp. 130-135

Abstract

This contribution will give a short introduction to the most important mechanic and acoustic parameters that are necessary to model and simulate frequency dependent sound propagation (dispersion) in isotropic but linear viscoelastic materials. Furthermore, several experimental techniques to measure these parameters will be discussed, like the dynamic-mechanical analysis and transient ultrasonic techniques. Finally it will be shown how to use the determined material parameters for the simulation of transient signals in a highly attenuative acoustic waveguide.

Application of Automatic Differentiation for the inverse parameter identification of complex-valued forward models

M. Webersen, F. Bause, B. Henning, 2015

Identification of temperature-dependent model parameters of ultrasonic piezo-composite transducers

M. Webersen, F. Bause, J. Rautenberg, B. Henning, in: AMA Conferences 2015, 2015, pp. 195-200

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.

Implementation and uncertainty analysis of a test device for electrical impedance measurements using vector network analyzers

M. Webersen, M. Karzellek, F. Bause, B. Henning, 2015

Methoden zur Zeit-Frequenz-Analyse bei der Untersuchung dispersionsbehafteter Signale

F. Bause, J. Rautenberg, N. Feldmann, L. Claes, B. Henning, 2014

Rekonstruktion der räumlichen Schallwechseldruckverteilung unter Berücksichtigung der Orthogonalität optischer und akustischer Achsen beim Schlierenverfahren

S. Olfert, L. Claes, B. Henning, in: Fortschritte der Akustik - DAGA 2014, 2014, pp. 541-542

Time-causal material modeling in the simulation of guided waves in circular viscoelastic waveguides

F. Bause, A. Schroder, J. Rautenberg, B. Henning, H. Gravenkamp, in: 2014 IEEE International Ultrasonics Symposium, 2014

DOI

Unsicherheitsanalyse eines Vorwärtsmodells zur Simulation transienter Wellenausbreitung im Hohlzylinder

F. Bause, D. Weber, J. Rautenberg, B. Henning, {VDE Verlag}, 2014

Model based sensitivity analysis of Leaky-Lamb wave propagation to the variation of viscous lubricant properties

F. Bause, C. Brückner, J. Miedl, B. Henning, in: Beiträge der 17. ITG/GMA-Fachtagung, {VDE Verlag}, 2014

Modellgestützte Analyse des Trocknungsverhaltens von Dispersionslacken aus Daten einer NIR-Multidetektoranordnung

C. Hoof, S. Appelhans, B. Henning, 2014

Abstract

Zur schnellen und berührungslosen Materialfeuchtebestimmung wird unter anderem die Infrarotreflexionsmessung ge-nutzt. In dieser Untersuchung wird das Trocknungsverhalten von Dispersionslack auf einem rauen Substrat mit einer Multidetektoranordnung untersucht. Durch diese Anordnung ist es möglich, gerichtete und diffuse Strahlungsanteile zu detektieren, wodurch zeitvariable Glanzeffekte an der Lackoberfläche miterfasst werden. Mit Hilfe eines Raytracing-Algorithmus wird die Trocknung eines Dispersionslackes simuliert und anhand von Messdaten mit einem FTIR-Spekt-rometer verifiziert.