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Foto: Universität Paderborn

Dr.-Ing. Leander Claes

Kontakt
Publikationen
Dr.-Ing. Leander Claes

Elektrische Messtechnik (EMT)

Wissenschaftlicher Mitarbeiter - Schallfeldsimulation, Fluidcharakterisierung

Telefon:
+49 5251 60-4950
Büro:
P1.5.17.3
Web:
Besucher:
Pohlweg 47-49
33098 Paderborn

Liste im Research Information System öffnen

2022

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



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


An explicit symplectic approach to solving the wave equation in moving media

V. Inguva, N. Feldmann, L. Claes, T. Koturbash, T. Hahn-Jose, V. Koutcherov, E. Kenig, Engineering Reports (2022), e12573

An explicit approach using symplectic time integration in conjunction with traditional finite difference spatial derivatives to solve the wave equation in moving media is presented. A simple operator split of this second order wave equation into two coupled first order equations is performed, allowing these split equations to be solved symplectically. Orders of symplectic time integration ranging from first to fourth along with orders of spatial derivatives ranging from second to sixth are explored. The case of cylindrical acoustic spreading in air under a constant velocity in a 2D square structured domain is considered. The variation of the computed time-of-flight, frequency, and wave length are studied with varying grid resolution and the deviations from the analytical solutions are determined. It was found that symplectic time integration interferes with finite difference spatial derivatives higher than second order causing unexpected results. This is actually beneficial for unstructured finite volume tools like OpenFOAM where second order spatial operators are the state-of-the art. Cylindrical acoustic spreading is simulated on an unstructured 2D triangle mesh showing that symplectic time integration is not limited to the spatial discretization paradigm and overcomes the numerical diffusion arising with the in-built numerical methods which hinder wave propagation.


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

<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>


2021

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

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.


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

DOI


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

DOI


pyfds 0.1.4 - modular field simulation tool

L. Claes, M. Webersen. pyfds 0.1.4 - modular field simulation tool. 2021.


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

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.



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

DOI


Messverfahren für die akustische Absorption in reinen Fluiden zur Bestimmung der Volumenviskosität

L. Claes, Universiät Paderborn, 2021

Die vollständige Beschreibung fluiddynamischer und akustischer Vorgänge setzt voraus, dass die Eigenschaften des Fluids hinlänglich bekannt sind.Während Fluidkenngrößen, wie etwa die Schallgeschwindigkeit oder die Scherviskosität, für viele Flüssigkeiten über weite Bereiche des thermodynamischen Zustandsraums bekannt sind, existieren für die Volumenviskosität nur eine geringe Anzahl Messdaten.In dieser Arbeit wird daher ein Messverfahren zur selektiven Bestimmung der Volumenviskosität von Flüssigkeiten, basierend auf der Absorption von Ultraschallwellen, entwickelt und realisiert.Schwerpunkte bilden dabei der simulationsgestützte Entwurf von Algorithmen zur Auswertung der Messsignale sowie die Analyse und Weiterentwicklung einer Messanordnung, basierend auf dem Puls-Echo-Verfahren. Neben der Absorption im Fluid treten dabei weitere Effekte (zum Beispiel Beugung oder unvollständige Reflexion) auf, die das akustische Signal schwächen oder anderweitig beeinflussen. Die Entwicklung von Verfahren zur Trennung dieser Effekte von der akustischen Absorption bildet daher einen weiteren Schwerpunkt dieser Arbeit.Abschließend wird die Volumenviskosität aus der gemessenen akustischen Absorption für unterschiedliche Fluide in verschiedenen thermodynamischen Zuständen unter Zuhilfenahme anderer bekannter Fluidkenngrößen bestimmt sowie eine Unsicherheitsbetrachtung durchgeführt.


Optimal experiment design with respect to electrode configurations for a piezoelectric problem

V. Schulze, S. Schmidt, B. Jurgelucks, N. Feldmann, L. Claes, 2021


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

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

DOI


Piezoelectric BC Modeling for Electrode Shapes with OED

V. Schulze, S. Schmidt, B. Jurgelucks, N. Feldmann, L. Claes, 2021


2020

A modular, scalable open-hardware platform for project-based laboratory courses in electrical engineering studies

T. Hetkämper, M. Krumme, D. Dreiling, L. Claes, in: SEFI 48th Annual Conference Proceedings - Engaging Engineering Education, SEFI, 2020, pp. 1309-1313


Estimation of acoustic wave non-linearity in ultrasonic measurement systems

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


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


Analoge Klangsynthese zur Vermittlung von Grundkenntnissen der Signalverarbeitung an Studierende nicht-technischer Fachrichtungen

M. Krumme, M. Webersen, L. Claes, Y. Webersen, in: Fortschritte der Akustik - DAGA 2020, 2020, pp. 542-545


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

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.


2019

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

DOI


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

DOI


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

DOI


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

DOI


Quantification of frequency-dependent absorption phenomena

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

DOI


Arbitrary sensitivity for inverse problems in piezoelectricity

B. Jurgelucks, V. Schulze, N. Feldmann, L. Claes, 2019


2018

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

DOI


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

DOI


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

DOI


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

DOI


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



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


2017

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)

DOI


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

DOI


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

DOI


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

DOI


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

DOI


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

DOI



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)

DOI


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


Miniaturized all-optical Sound Pressure Sensor

B. Fischer, L. Claes, in: INTER-NOISE 2016, Deutsche Gesellschaft für Akustik e.V., 2016



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

B. Jurgelucks, L. Claes, in: AD2016 The 7th International Conference on Algorithmic Differentiation, 2016, pp. 99-102


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


2015

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

DOI


2014

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

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



2013

Influence of angular radiated ultrasound waves on the Schlieren tomogram

S. Olfert, L. Claes, B. Henning, in: Proceedings of the International Conference on Acoustics, DEGA, 2013, pp. 477-480


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