TY - THES A1 - Gravenkamp, Hauke T1 - Numerical methods for the simulation of ultrasonic guided waves N2 - Ultrasonic guided waves offer a wide range of applications in fields such as non-destructive testing, structural health monitoring or material characterization. They can be excited in thin-walled structures and propagate over comparably long distances. Due to their complex and dispersive propagation behavior, numerical methods are often required in order to analyze the guided wave modes that can be excited in a given structure and to simulate their interaction with defects. In the work presented in this thesis, highly efficient numerical methods have been developed that are specifically optimized for guided wave problems. The formulation is based on the Scaled Boundary Finite Element Method (SBFEM). The SBFEM is a semi-analytical method which evolved from the concept of Finite Elements but requires the discretization of the boundary of the computational domain only. To compute dispersion curves and mode shapes of guided waves, only the cross-section of the waveguide is discretized in the Finite Element sense, while the direction of propagation is described analytically. The wavenumbers of guided wave modes and the corresponding mode shapes are obtained as the eigenvalues and eigenvectors of a frequency-dependent Hamiltonian matrix. For the discretization, higher-order spectral elements are employed, leading to very low computational costs compared to traditional Finite Elements. Particular formulations are presented for plate structures as well as axisymmetric waveguides, where only the throughthickness direction has to be discretized. For the cases where the waveguide is embedded in or coupled to a quasi-infinite medium, a dashpot boundary condition is proposed in order to account for the effect of waves being transmitted into the surrounding medium. Though this approach is not exact, it leads to sufficiently accurate results for practical applications, while the computational costs are typically reduced by several orders of magnitude compared to other Finite Element based approaches. As a particular application, an experimental set-up for material characterization is discussed, where the elastic constants of the waveguide’s material are obtained from the analysis of waves propagating through the waveguide. A novel solution procedure is proposed in this work, where each mode of interest is traced over the required frequency range. The solutions are obtained by means of inverse iteration. To demonstrate the potential of the SBFEM for non-destructive testing applications, the interaction of guided wave modes with cracks in plates is simulated in the time domain for several examples. Particularly for the modeling of cracked structures, the SBFEM is very well suited, since the side-faces of the crack do not require discretization and the stress-singularity at the crack tip does not introduce additional difficulties. Hence, the computational costs can be reduced by typically a factor 100 compared to traditional Finite Elements and the meshing is straightforward. T3 - BAM Dissertationsreihe - 116 KW - guided wave KW - numerical methods KW - scaled boundary finite element method KW - ultrasound PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-428 SN - 978-3-9816380-4-2 SN - 1613-4249 VL - 116 SP - 1 EP - 195 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-42 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Song, C. T1 - Scaled Boundary Finite Element Method zur effizienten Simulation geführter Ultraschallwellen T2 - DGZfP-Jahrestagung 2013 T2 - DGZfP-Jahrestagung 2013 CY - Dresden, Germany DA - 2013-05-06 PY - 2013 AN - OPUS4-28550 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Song, C. A1 - Birk, C. T1 - Modelling ultrasonic waves in solid waveguides of arbitrary cross-section T2 - AIA-DAGA 2013 Conference on Acoustics T2 - AIA-DAGA 2013 Conference on Acoustics CY - Meran, Italy DA - 2013-03-18 PY - 2013 AN - OPUS4-28551 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Man, H. A1 - Song, Ch. A1 - Birk, C. T1 - Numerical computation of dispersion relations in three-dimensional waveguides T2 - Australian Conference on the Mechanics of Structures and Materials (ACMSM 22) T2 - Australian Conference on the Mechanics of Structures and Materials (ACMSM 22) CY - Sydney, Australia DA - 2012-12-11 PY - 2012 AN - OPUS4-28495 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Saputra, A. A1 - Birk, C. A1 - Song, Ch. T1 - Numerical modelling of Lamb waves in cracked plates using the scaled boundary finite element method T2 - Australian Conference on the Mechanics of Structures and Materials (ACMSM 22) T2 - Australian Conference on the Mechanics of Structures and Materials (ACMSM 22) CY - Sydney, Australia DA - 2012-12-11 PY - 2012 AN - OPUS4-28496 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - A numerical approach for the computation of dispersion relations for plate structures using the scaled boundary finite element method JF - Journal of sound and vibration N2 - In this paper, a method is presented for the numerical computation of dispersion properties and mode shapes of guided waves in plate structures. The formulation is based on the Scaled Boundary Finite Element Method. The through-thickness direction of the plate is discretized in the finite element sense, while the direction of propagation is described analytically. This leads to a standard eigenvalue problem for the calculation of wave numbers. The proposed method is not limited to homogeneous plates. Multi-layered composites as well as structures with continuously varying material parameters in the direction of thickness can be modeled without essential changes in the formulation. Higher-order elements have been employed for the finite element discretization, leading to excellent convergence for complex structures. It is shown by numerical examples that this method provides highly accurate results with a small number of nodes while avoiding numerical problems and instabilities. KW - Scaled boundary finite element method KW - Lamb waves KW - Dispersion KW - Non-destructive testing KW - Composites KW - Functionally graded materials PY - 2012 DO - https://doi.org/10.1016/j.jsv.2012.01.029 SN - 0022-460X SN - 1095-8568 VL - 331 IS - 11 SP - 2543 EP - 2557 PB - Academic Press CY - London AN - OPUS4-25743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke T1 - The simultion of ultrasonic guided waves using the Scaled Boundary Finite Element Method T2 - Forum Braunschweiger Akustiker T2 - Forum Braunschweiger Akustiker CY - Helmstedt, Germany DA - 2012-05-31 PY - 2012 AN - OPUS4-25995 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - Numerische Berechnung der Dispersionseigenschaften von Lambwellen in Platten mit beliebiger Materialzusammensetzung T2 - DAGA 2012 - 38. Jahrestagung für Akustik - Fortschritte der Akustik N2 - Für alle Anwendungen geführter Wellen, beispielsweise in der zerstörungsfreien Materialprüfung, ist die exakte und effiziente Berechnung von Dispersionseigenschaften erforderlich. Dabei müssen für eine gegebene Frequenz die Anzahl der ausbreitungsfähigen Moden und deren Wellenzahlen sowie Phasen- und Gruppengeschwindigkeiten berechnet werden. Für den Fall von Lambwellen in homogenen isotropen Platten existieren analytische Gleichungen für die Wellenzahlen, die sich mit numerischen Nullstellensuchverfahren lösen lassen. Für komplexere Strukturen oder dreidimensionale, nicht rotationssymmetrische Wellenleiter ist die Entwicklung numerischer Methoden erforderlich. In der vorliegenden Arbeit wird ein numerisches Verfahren, basierend auf der Scaled Boundary Finite Element Method (SBFEM) [1] vorgestellt. Mit diesem lassen sich Dispersionseigenschaften von beliebigen Wellenleitern sehr effizient berechnen. Ergebnisse werden für den Fall von Wellen in Platten mit komplexer Materialzusammensetzung präsentiert. T2 - DAGA 2012 - 38. Jahrestagung für Akustik - Fortschritte der Akustik CY - Darmstadt, Deutschland DA - 2012-03-19 KW - Ultraschall KW - Lambwellen KW - Dispersion KW - Scaled boundary finite element method PY - 2012 SP - 1 EP - 2 PB - Deutsche Gesellschaft für Akustik e.V. AN - OPUS4-25978 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Saputra, A. A. A1 - Song, C. A1 - Prager, Jens ED - Linde, B. B. J. ED - Paczkowski, J. ED - Ponikwicki, N. T1 - Detection of defects in thin-walled structures by means of lamb waves T2 - International congress on ultrasonics N2 - In this paper the Scaled Boundary Finite Element Method (SBFEM) is applied for the simulation of Lamb waves in cracked plates. This method is highly advantageous to study the interaction of different Lamb wave modes with cracks as the crack is not discretized and no refinement is required around the crack tip. Numerical examples are presented for the reflection of the fundamental symmetric and antisymmetric modes from cracks of different depth. The spatial Fourier transformation is employed to calculate the amplitudes of reflected Lamb wave modes. The results reveal possibilities to obtain details of the crack geometry in non-destructive testing and structural health monitoring applications. T2 - International congress on ultrasonics CY - Gdansk, Poland DA - 05.09.2011 KW - Lamb waves KW - Scaled boundary finite element method KW - Simulation KW - Crack detection PY - 2012 SN - 978-0-7354-1019-0 DO - https://doi.org/10.1063/1.3703223 SN - 0094-243X N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings IS - 1433 SP - 443 EP - 446 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26203 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prager, Jens A1 - Gravenkamp, Hauke A1 - Rahman, Mehbub-Ur A1 - Köppe, Enrico T1 - Einsatz geführter Wellen für die Ultraschallprüfung JF - Technisches Messen N2 - Der Einsatz geführter Wellen für die zerstörungsfreie Prüfung mit Ultraschall eröffnet neue Möglichkeiten, räumlich ausgedehnte Bauteile mit begrenzter Zugänglichkeit auf ihre Integrität zu prüfen und gewinnt daher zunehmend an Bedeutung. Dieser Artikel behandelt die physikalischen Grundlagen der Schallausbreitung. Deren Verständnis bildet die Grundlage für die Entwicklung geeigneter Prüfsysteme. An Beispielen werden verschiedene Möglichkeiten zur Simulation der Schallausbereitung vorgestellt. Aktuelle Lösungsansätze zur Prüfung von plattenförmigen Strukturen und von Rohrleitungen werden beschrieben, wobei besonders auf die Sensortechnik und die speziellen Anforderungen an die Prüfhardware eingegangen wird. ----------------------------------------------------------------------------------------------------------------------------------- Guided waves are widely used for non-destructive testing using ultrasound. Recently, the method has become increasingly important for integrity tests of spatially extended components with limited accessibility. This article discusses the basic physics of the sound propagation of guided waves. Their understanding forms the basis for the successful development of adapted inspection systems. Examples for simulating the wave propagation using different methods are presented. Current approaches for the inspection of plate-like structures and pipelines are described with focus on sensor technology and the specific requirement on the test hardware. KW - Zerstörungsfreie Prüfung KW - Geführte Wellen KW - Ultraschallprüfung KW - Non-destructive evaluation KW - Guided waves KW - Ultrasound PY - 2012 DO - https://doi.org/10.1524/teme.2012.0168 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 79 IS - 5 SP - 251 EP - 261 PB - Oldenbourg CY - München AN - OPUS4-26206 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Man, H. A1 - Song, C. A1 - Prager, Jens T1 - The computation of dispersion relations for three-dimensional elastic waveguides using the scaled boundary finite element method JF - Journal of sound and vibration N2 - In this paper, a numerical approach for the computation of dispersion relations for three-dimensional waveguides with arbitrary cross-section is proposed. The formulation is based on the Scaled Boundary Finite Element Method (SBFEM). It is an extension of the approach previously derived for plate structures. It is shown that the wavenumbers of guided waves in a waveguide can be obtained as the eigenvalues of the Z matrix, which is well known in the SBFEM. The Hamiltonian properties of this matrix are utilized to derive an efficient way to compute the group velocities of propagating waves as eigenvalue derivatives. The cross-section of the waveguide is discretized using higher-order spectral elements. It is discussed in detail how symmetry axes can be utilized to reduce computational costs. In order to sort the solutions at different frequencies, a mode-tracking algorithm is proposed, based on the Padé expansion. KW - Guided waves KW - Simulation KW - Dispersion KW - Scaled boundary finite element method PY - 2013 DO - https://doi.org/10.1016/j.jsv.2013.02.007 SN - 0022-460X SN - 1095-8568 VL - 332 IS - 15 SP - 3756 EP - 3771 PB - Academic Press CY - London AN - OPUS4-28837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Saputra, A. A. A1 - Chongmin, Song T1 - Detection of defects in thin-walled structures by means of Lamb waves T2 - International Congress on Ultrasonics 2011 T2 - International Congress on Ultrasonics 2011 CY - Gdansk, Poland DA - 2011-09-05 PY - 2011 AN - OPUS4-24332 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - Numerical computation of dispersion relations in wave guides JF - Proceedings in applied mathematics and mechanics : PAMM N2 - In this paper a numerical approach, based on the Scaled Boundary Finite Element Method (SBFEM), is described to obtain dispersion relations for propagating modes in wave guides. While the formulation is developed for plate structures, it can easily be extended to wave guides with arbitrary cross-section. The cross-section is discretized in the Finite Element sense while all equations remain analytical in the direction of propagation. The wave numbers of all propagating modes are obtained as the solutions of a standard eigenvalue problem. The group velocities can be calculated accurately as the eigenvalue derivatives. The use of higher-order elements drastically increases the efficiency and accuracy of the computation. This approach can be used for wave guides with arbitrary distribution of material parameters. KW - Guided waves KW - Dispersion KW - Group velocity KW - Scaled boundary finite element method PY - 2012 DO - https://doi.org/10.1002/pamm.201210256 SN - 1617-7061 VL - 12 IS - 1 SP - 535 EP - 536 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-27750 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Saputra, A. A. A1 - Birk, C. A1 - Song, C. A1 - Gravenkamp, Hauke ED - Samali, ED - Attard, ED - Song, T1 - Numerical modelling of lamb waves in cracked plates using the scaled boundary finite element method T2 - ACMSM 22 - Australasian conference on the mechanics of structures and materials - From materials to structures: advancement through innovation T2 - ACMSM 22 - Australasian conference on the mechanics of structures and materials CY - Sydney, Australia DA - 2012-12-11 KW - Lamb waves KW - Scaled boundary finite element method KW - Crack detection KW - Continued fractions PY - 2013 SN - 978-0-415-63318-5 SP - 927 EP - 932 PB - Taylor & Francis AN - OPUS4-27751 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Man, H. A1 - Birk, C. A1 - Song, C. ED - Samali, ED - Attard, ED - Song, T1 - Numerical computation of dispersion relations in three-dimensional waveguides T2 - ACMSM 22 - Australasian conference on the mechanics of structures and materials - From materials to structures: advancement through innovation T2 - ACMSM 22 - Australasian conference on the mechanics of structures and materials CY - Sydney, Australia DA - 2012-12-11 KW - Guided waves KW - Dispersion KW - Scaled boundary finite element method KW - Non-destructive testing KW - Structural health monitoring PY - 2013 SN - 978-0-415-63318-5 SP - 897 EP - 902 PB - Taylor & Francis AN - OPUS4-27752 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Song, C. T1 - Numerical computation of dispersion relations in wave guides T2 - GAMM 2012, 83rd Annual Meeting of the International Association of Applied Mathematics and Mechanics T2 - GAMM 2012, 83rd Annual Meeting of the International Association of Applied Mathematics and Mechanics CY - Darmstadt, Germany DA - 2012-03-26 PY - 2012 AN - OPUS4-26220 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Song, C. T1 - Numerische Berechnung der Dispersionseigenschaften von Lambwellen in Platten mit beliebiger Materialzusammensetzung T2 - DAGA 2012. 38. Jahrestagung für Akustik T2 - DAGA 2012. 38. Jahrestagung für Akustik CY - Darmstadt, Germany DA - 2012-03-19 PY - 2012 AN - OPUS4-26221 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Subhani, M. A1 - Li, J. A1 - Gravenkamp, Hauke A1 - Samali, B. T1 - Effect of elastic modulus and Poisson's ratio on guided wave dispersion using transversely isotropic material modelling JF - Advanced materials research N2 - Timber poles are commonly used for telecommunication and power distribution networks, wharves or jetties, piling or as a substructure of short span bridges. Most of the available techniques currently used for non-destructive testing (NDT) of timber structures are based on one-dimensional wave theory. If it is essential to detect small sized damage, it becomes necessary to consider guided wave (GW) propagation as the behaviour of different propagating modes cannot be represented by one-dimensional approximations. However, due to the orthotropic material properties of timber, the modelling of guided waves can be complex. No analytical solution can be found for plotting dispersion curves for orthotropic thick cylindrical waveguides even though very few literatures can be found on the theory of GW for anisotropic cylindrical waveguide. In addition, purely numerical approaches are available for solving these curves. In this paper, dispersion curves for orthotropic cylinders are computed using the scaled boundary finite element method (SBFEM) and compared with an isotropic material model to indicate the importance of considering timber as an anisotropic material. Moreover, some simplification is made on orthotropic behaviour of timber to make it transversely isotropic due to the fact that, analytical approaches for transversely isotropic cylinder are widely available in the literature. Also, the applicability of considering timber as a transversely isotropic material is discussed. As an orthotropic material, most material testing results of timber found in the literature include 9 elastic constants (three elastic moduli and six Poisson's ratios), hence it is essential to select the appropriate material properties for transversely isotropic material which includes only 5 elastic constants. Therefore, comparison between orthotropic and transversely isotropic material model is also presented in this article to reveal the effect of elastic moduli and Poisson's ratios on dispersion curves. Based on this study, some suggestions are proposed on selecting the parameters from an orthotropic model to transversely isotropic condition. KW - Timber KW - Guided wave KW - Transversely isotropic material KW - Orthotropic material KW - Dispersion curves PY - 2013 DO - https://doi.org/10.4028/www.scientific.net/AMR.778.303 SN - 1022-6680 SN - 1662-8985 VL - 778 SP - 303 EP - 311 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-29019 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke T1 - Scaled Boundary Finite Element Method zur Simulation geführter Ultraschallwellen T2 - IZFP Seminar 2013 T2 - IZFP Seminar 2013 CY - Saarbrücken, Germany DA - 2013-07-15 PY - 2013 AN - OPUS4-29001 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke T1 - Numerische Methoden zur Simulation geführter Ultraschallwellen T2 - Doktorandenkolloquium des Institutes für Konstruktionstechnik der TU Braunschweig T2 - Doktorandenkolloquium des Institutes für Konstruktionstechnik der TU Braunschweig CY - Braunschweig, Germany DA - 2013-08-15 PY - 2013 AN - OPUS4-29002 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - Numerical simulation of ultrasonic guided waves using the scaled boundary finite element method T2 - IUS 2012 - IEEE International Ultrasonics Symposium (Proceedings) N2 - The formulation of the Scaled Boundary Finite Element Method is applied for the computation of dispersion properties of ultrasonic guided waves. The cross-section of the waveguide is discretized in the Finite Element sense, while the direction of propagation is described analytically. A standard eigenvalue problem is derived to compute the wave numbers of propagating modes. This paper focuses on cylindrical waveguides, where only a straight line has to be discretized. Higher-order elements are utilized for the discretization. As examples, dispersion curves are computed for a homogeneous pipe and a layered cylinder. T2 - 2012 IEEE International Ultrasonics Symposium (IUS) CY - Dresden, Germany DA - 2012-10-07 KW - Guided waves KW - Simulation KW - Dispersion KW - Scaled boundary finite element method PY - 2012 SN - 978-1-4673-4562-0 DO - https://doi.org/10.1109/ULTSYM.2012.0673 SN - 1948-5719 SP - 2686 EP - 2689 AN - OPUS4-29665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Prager, Jens T1 - Computation of dispersion relations in wave guides of arbitrary cross section T2 - World Congress on Computational Mechanics (WCCM) 2012 T2 - World Congress on Computational Mechanics (WCCM) 2012 CY - São Paulo, Brazil DA - 2012-07-08 PY - 2012 AN - OPUS4-26718 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Saputra, A. A. A1 - Song, C. T1 - The simulation of Lamb waves in a cracked plate using the scaled boundary finite element method JF - The journal of the Acoustical Society of America : JASA N2 - The scaled boundary finite element method is applied to the simulation of Lamb waves for ultrasonic testing applications. With this method, the general elastodynamic problem is solved, while only the boundary of the domain under consideration has to be discretized. The reflection of the fundamental Lamb wave modes from cracks of different geometry in a steel plate is modeled. A test problem is compared with commercial finite element software, showing the efficiency and convergence of the scaled boundary finite element method. A special formulation of this method is utilized to calculate dispersion relations for plate structures. For the discretization of the boundary, higher-order elements are employed to improve the efficiency of the simulations. The simplicity of mesh generation of a cracked plate for a scaled boundary finite element analysis is illustrated. KW - Lamb waves KW - Scaled boundary finite element method KW - Dispersion KW - Structural dynamics KW - Cracks PY - 2012 DO - https://doi.org/10.1121/1.4740478 SN - 0001-4966 SN - 1520-8524 VL - 132 IS - 3 SP - 1358 EP - 1367 PB - AIP CY - Melville, NY, USA AN - OPUS4-27115 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Bause, F. A1 - Song, C. T1 - On the computation of dispersion curves for axisymmetric elastic waveguides using the scaled boundary finite element method JF - Computers & structures N2 - In this paper we propose an algorithm to compute specific parts of the dispersion curves for elastic waveguides. The formulation is based on an axisymmetric representation of the Scaled Boundary Finite Element Method, where the wavenumbers of propagating modes are obtained as solutions of a Hamiltonian eigenvalue problem. The novel solution procedure involves tracing selected modes over a given frequency range and computing the corresponding solutions by means of inverse iteration. The resulting algorithm is applied in the context of material characterization, where the efficiency of the computation is crucial. KW - Guided waves KW - Dispersion KW - Numerical methods KW - Scaled Boundary Finite Element Method KW - Cylinders PY - 2014 DO - https://doi.org/10.1016/j.compstruc.2013.10.014 SN - 0045-7949 SN - 0366-7138 VL - 131 SP - 46 EP - 55 PB - Pergamon Press CY - Oxford AN - OPUS4-29701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Mahbube, Subhani A1 - Li, J. A1 - Bijan, Samali T1 - Effect of elastic modulus and Poisson´s ratio on guided wave dispersion using transversely isotropic material modelling T2 - SHATIS, International Conference on Structural Health Assessment of Timber Structures T2 - SHATIS, International Conference on Structural Health Assessment of Timber Structures CY - Trento, Italy DA - 2013-09-04 PY - 2013 AN - OPUS4-29744 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Song, Ch. T1 - Modeling ultrasonic guided waves in embedded structures using the Scaled Boundary Finite Element Method T2 - APCOM, 5TH ASIA PACIFIC CONGRESS ON COMPUTATIONAL MECHANICS T2 - APCOM, 5TH ASIA PACIFIC CONGRESS ON COMPUTATIONAL MECHANICS CY - Singapore DA - 2013-12-11 PY - 2013 AN - OPUS4-29155 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Bause, F. A1 - Rautenberg, J. A1 - Henning, B. ED - Declercq, N. F. T1 - Model Based Sensitivity Analysis in the Determination of Viscoelastic Material Properties Using Transmission Measurements through Circular Waveguides T2 - Physics Procedia N2 - 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. T2 - ICU International Congress on Ultrasonics 2015 CY - Georgia Tech Lorraine, Metz, France DA - 10.05.2015 KW - Ultrasonic material determination KW - Sensitivity KW - Inverse problem PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-372551 DO - https://doi.org/10.1016/j.phpro.2015.08.127 SN - 1875-3892 VL - 70 SP - 204 EP - 207 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-37255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke T1 - A remark on the computation of shear-horizontal and torsional modes in elastic waveguides JF - Ultrasonics N2 - When modeling the propagation of elastic guided waves in plates or cylinders, Finite Element based numerical methods such as the Scaled Boundary Finite Element Method (SBFEM) or the Semi-Analytical Finite Element (SAFE) Method lead to an eigenvalue problem to be solved at each frequency. For the particular case of shear horizontal modes in a homogeneous plate or torsional modes in a homogeneous cylinder, the problem can be drastically simplified. The eigenvalues become simple functions of the frequency, while the eigenvectors are constant. The current contribution discusses how this behavior is represented in the numerical formulation and derives the expressions for the eigenvalues and eigenvectors as well as the dynamic stiffness matrix of infinite elastic waveguides. KW - Guided waves KW - Shear-horizontal modes KW - Torsional modes KW - Scaled Boundary Finite Element Method PY - 2016 DO - https://doi.org/10.1016/j.ultras.2016.03.003 SN - 0041-624X VL - 2016/69 SP - 25 EP - 28 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-36429 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Song, C. T1 - Computation of dispersion curves for embedded waveguides using a dashpot boundary condition JF - The journal of the Acoustical Society of America N2 - In this paper a numerical approach is presented to compute dispersion curves for solid waveguides coupled to an infinite medium. The derivation is based on the scaled boundary finite element method that has been developed previously for waveguides with stress-free surfaces. The effect of the surrounding medium is accounted for by introducing a dashpot boundary condition at the interface between the waveguide and the adjoining medium. The damping coefficients are derived from the acoustic impedances of the surrounding medium. Results are validated using an improved implementation of an absorbing region. Since no discretization of the surrounding medium is required for the dashpot approach, the required number of degrees of freedom is typically 10 to 50 times smaller compared to the absorbing region. When compared to other finite element based results presented in the literature, the number of degrees of freedom can be reduced by as much as a factor of 4000. PY - 2014 DO - https://doi.org/10.1121/1.4864303 SN - 0001-4966 SN - 1520-8524 VL - 135 IS - 3 SP - 1127 EP - 1138 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-30324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, Ch. T1 - Innovative numerische Methoden zur Simulation geführter Ultraschallwellen T2 - DGZfP-Jahrestagung 2014 T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 2014-05-26 PY - 2014 AN - OPUS4-30791 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. T1 - Innovative numerische Methoden zur Simulation geführter Ultraschallwellen T2 - DGZfP-Jahrestagung 2014 (Proceedings) N2 - Geführte Ultraschallwellen bieten eine Vielzahl von Einsatzmöglichkeiten in der Zerstörungsfreien Prüfung, der Zustandsüberwachung sowie der Materialcharakterisierung. Insbesondere für Rohrleitungen und ausgedehnte Plattenstrukturen ist eine Vielzahl von auf geführten Wellen basierenden Verfahren in der Entwicklung und teilweise bereits im Einsatz. Aufgrund des komplexen Ausbreitungsverhaltens geführter Wellen werden numerische Verfahren (etwa die Finite Elemente Methode (FEM) oder die Randelementemethode (BEM)) zur Simulation der Wellenausbreitung sowie der Wechselwirkung mit Defekten in Wellenleitern angewendet. Diese Methoden sind für große Strukturen extrem rechenintensiv und umständlich in der Anwendung. Ein ungleich effizienteres Verfahren wurde kürzlich von den Autoren auf Grundlage der Scaled Boundary Finite Element Method entwickelt. Ein semi-analytischer Ansatz erlaubt die Modellierung beliebig ausgedehnter Strukturen bei extrem kurzen Rechenzeiten. Die Wechselwirkung geführter Wellen mit Rissen kann auf besonders elegante und exakte Weise beschrieben werden. Mit dieser Methode können die komplexen Vorgänge in Wellenleitern innerhalb weniger Sekunden modelliert werden. T2 - DGZfP-Jahrestagung 2014 CY - Potsdam, Germany DA - 26.04.2014 PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-313610 SN - 978-3-940283-61-0 IS - DGZfP-BB 148 SP - Poster 66, 1 EP - 6 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-31361 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhne, Christian A1 - Prager, Jens A1 - Gravenkamp, Hauke T1 - Computation of dispersion relations for axially symmetric guided waves in cylindrical structures by means of a spectral decomposition method JF - Ultrasonics N2 - In this paper, a method to determine the complex dispersion relations of axially symmetric guided waves in cylindrical structures is presented as an alternative to the currently established numerical procedures. The method is based on a spectral decomposition into eigenfunctions of the Laplace operator on the cross-section of the waveguide. This translates the calculation of real or complex wave numbers at a given frequency into solving an eigenvalue problem. Cylindrical rods and plates are treated as the asymptotic cases of cylindrical structures and used to generalize the method to the case of hollow cylinders. The presented method is superior to direct root-finding algorithms in the sense that no initial guess values are needed to determine the complex wave numbers and that neither starting at low frequencies nor subsequent mode tracking is required. The results obtained with this method are shown to be reasonably close to those calculated by other means and an estimate for the achievable accuracy is given. KW - Guided waves KW - Numerical method KW - Spectral decomposition KW - Dispersion KW - Cylinders PY - 2015 DO - https://doi.org/10.1016/j.ultras.2015.06.011 SN - 0041-624x VL - 63 SP - 54 EP - 64 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-31946 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke T1 - Novel approaches for the simulation of ultrasonic guided waves T2 - ECNDT 2014 T2 - ECNDT 2014 CY - Prag (Tschechien) DA - 2014-10-06 PY - 2014 AN - OPUS4-31979 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Bause, F. A1 - Schröder, A. A1 - Rautenberg, J. A1 - Henning, B. T1 - Time-causal material modeling in the simulation of guided waves in circular viscoelastic waveguides T2 - 2014 IEEE International Ultrasonics Symposium T2 - 2014 IEEE International Ultrasonics Symposium CY - Chicago (USA) DA - 2014-09-03 PY - 2014 AN - OPUS4-31989 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Song, C. T1 - Simulation of guided waves in solids using the Scaled Boundary Finite Element Method T2 - Wolrd Congress on Computational Mechanics, WCCM 2014 T2 - Wolrd Congress on Computational Mechanics, WCCM 2014 CY - Barcelona (Spanien) DA - 2014-07-20 PY - 2014 AN - OPUS4-31990 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bause, F. A1 - Schröder, A. A1 - Rautenberg, J. A1 - Henning, B. A1 - Gravenkamp, Hauke T1 - Time-causal material modeling in the simulation of guided waves in circular viscoelastic waveguides T2 - IUS 2014 - IEEE International ultrasonics symposium (Proceedings) N2 - For the description of linear viscoelasticity, the fractional Zener model may be used. Based on the spectral decomposition of the elasticity matrix as proposed by Theocaris, we generalize the one-dimensional analysis of the material model into three dimensions and discuss appropriate simplifications to reduce the amount of unknowns for the material description. Then, a decomposition approach that considers the real valued frequency dependence of the viscoelastic moduli and the real valued frequency dependence of their attenuation separately is proposed. The Scaled Boundary Finite Element Method is used for the efficient computation of the phase velocity dispersion and the modal wave fields given a frequency dependent but real valued viscoelasticity matrix. Utilizing the modal expansion approach, the transmitting and receiving transducer are taken into account to compute the modal amplitudes. Combining these modal amplitudes, the phase velocity dispersion and re-introducing the viscoelastic attenuation results in a transfer function of the viscoelastic waveguide including excitation and receiving conditions. The performance of the proposed simulation model is shown by comparison to measurements taken on a polypropylene sample. T2 - IUS 2014 - IEEE International ultrasonics symposium CY - Chicago, IL, USA DA - 03.09.2014 PY - 2014 SN - 978-1-4799-7049-0 DO - https://doi.org/10.1109/ULTSYM.2014.0333 SP - 1348 EP - 1351 AN - OPUS4-31869 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Song, C. T1 - The computation of dispersion relations for axisymmetric waveguides using the Scaled Boundary Finite Element Method JF - Ultrasonics N2 - This paper addresses the computation of dispersion curves and mode shapes of elastic guided waves in axisymmetric waveguides. The approach is based on a Scaled Boundary Finite Element formulation, that has previously been presented for plate structures and general three-dimensional waveguides with complex cross-section. The formulation leads to a Hamiltonian eigenvalue problem for the computation of wavenumbers and displacement amplitudes, that can be solved very efficiently. In the axisymmetric representation, only the radial direction in a cylindrical coordinate system has to be discretized, while the circumferential direction as well as the direction of propagation are described analytically. It is demonstrated, how the computational costs can drastically be reduced by employing spectral elements of extremely high order. Additionally, an alternative formulation is presented, that leads to real coefficient matrices. It is discussed, how these two approaches affect the computational efficiency, depending on the elasticity matrix. In the case of solid cylinders, the singularity of the governing equations that occurs in the center of the cross-section is avoided by changing the quadrature scheme. Numerical examples show the applicability of the approach to homogeneous as well as layered structures with isotropic or anisotropic material behavior. KW - Guided waves KW - Numerical methods KW - Scaled Boundary Finite Element Method KW - Dispersion KW - Cylinders PY - 2014 DO - https://doi.org/10.1016/j.ultras.2014.02.004 SN - 0041-624x VL - 54 IS - 5 SP - 1373 EP - 1385 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-30491 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Song, C. T1 - Numerical modeling of elastic waveguides coupled to infinite fluid media using exact boundary conditions JF - Computers & structures N2 - The simulation of guided waves in plate structures and cylinders coupled to infinite fluids is addressed. The approach is based on the Scaled Boundary Finite Element Method. Only a straight line is discretized that represents the through-thickness direction or the radial direction. The surrounding fluid is accounted for by employing a damping boundary condition that is based on the analytical description of the radiation impedance. Since the radiation impedance is a function of the wavenumber in the waveguide, an iterative solution procedure is applied. The algorithm is highly efficient while the results are in agreement with the Global Matrix Method. KW - Guided waves KW - Embedded KW - Fluid KW - Ultrasound KW - Scaled boundary finite element method PY - 2014 DO - https://doi.org/10.1016/j.compstruc.2014.05.010 SN - 0045-7949 SN - 0366-7138 VL - 141 SP - 36 EP - 45 PB - Pergamon Press CY - Oxford AN - OPUS4-30896 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krome, Fabian A1 - Gravenkamp, Hauke ED - Every, A. T1 - Analyzing modal behavior of guided waves using high order eigenvalue derivatives JF - Ultrasonics N2 - This paper presents a mode-tracing approach for elastic guided waves based on analytically computed derivatives and includes a study of interesting phenomena in the dispersion curve representation. Numerical simulation is done by means of the Scaled Boundary Finite Element Method (SBFEM). Two approaches are used to identify the characteristics of the resulting wave modes: Taylor approximation and Padé approximation. Higher order differentials of the underlying eigenvalue problem are the basis for these approaches. Remarkable phenomena in potentially critical frequency regions are identified and the tracing approach is adapted to these regions. Additionally, a stabilization of the solution process is suggested. KW - Guided waves KW - Mode-tracing KW - Eigenvalue problem derivatives KW - Ultrasound KW - Scaled Boundary Finite Element Method PY - 2016 DO - https://doi.org/10.1016/j.ultras.2016.05.014 SN - 0041-624X VL - 2016 IS - 71 SP - 75 EP - 85 PB - Elsevier B.V. AN - OPUS4-38076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Van, J. T1 - Modeling ultrasonic waves in elastic waveguides of arbitrary cross-section embedded in infinite solid medium JF - Computers & structures N2 - An approach is presented to model elastic waveguides of arbitrary cross-section coupled to infinite solid media. The formulation is based on the scaled boundary-finite element method. The surrounding medium is approximately accounted for by a dashpot boundary condition derived from the acoustic impedances of the infinite medium. It is discussed under which circumstances this approximation leads to sufficiently accurate results. Computational costs are very low, since the surrounding medium does not require discretization and the number of degrees of freedom on the cross-section is significantly reduced by utilizing higher-order spectral elements. KW - Guided waves KW - Scaled boundary finite element method KW - Leaky waves KW - Ultrasound PY - 2015 DO - https://doi.org/10.1016/j.compstruc.2014.11.007 SN - 0045-7949 SN - 0366-7138 VL - 149 SP - 61 EP - 71 PB - Pergamon Press CY - Oxford AN - OPUS4-32348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Bause, F. A1 - Rautenberg, J. A1 - Henning, B. T1 - Model based sensitivity analysis in the determination of viscoelastic material properties using transmission measurements through circular waveguides T2 - International Congress on Ultrasonics 2015 T2 - International Congress on Ultrasonics 2015 CY - Metz, Frankreich DA - 2015-05-10 PY - 2015 AN - OPUS4-33196 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Krome, Fabian T1 - Simulation von Ultraschallwellen in ausgedehnten Strukturen T2 - DACH-Jahrestagung Salzburg 2015 T2 - DACH-Jahrestagung Salzburg 2015 CY - Salzburg, Österreich DA - 2015-05-11 PY - 2015 AN - OPUS4-33197 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke T1 - Modelling ultrasonic waves using the Scaled Boundary Finite Element T2 - Seminar in mechanical engineering, Indian Institute of Technology T2 - Seminar in mechanical engineering, Indian Institute of Technology CY - Chennai (Indien) DA - 2015-04-06 PY - 2015 AN - OPUS4-33567 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, Ch. A1 - Birk, C. T1 - Numerical modeling of waveguides embedded in infinite media T2 - International Congress on Sound and Vibration 2015 T2 - International Congress on Sound and Vibration 2015 CY - Firenze (Italien) DA - 2015-07-12 PY - 2015 AN - OPUS4-33740 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gravenkamp, Hauke A1 - Birk, C. A1 - Song, C. T1 - Simulation of elastic guided waves interacting with defects in arbitrarily long structures using the scaled boundary finite element method JF - Journal of computational physics N2 - In this paper, an approach is presented to model the propagation of elastic waves and their interaction with defects in plate structures. The formulation is based on the Scaled Boundary Finite Element Method (SBFEM), a general semi-analytical method requiring the discretization of boundaries only. For a homogeneous finite or infinite plate section, only the through-thickness direction of the plate is discretized. To describe a defect, the full boundary of a short plate section of irregular shape is discretized. High-order spectral elements are employed for the discretization. The formulation for infinite plates can model the transmission into an unbounded domain exactly. Results are compared with conventional Finite Element Analyses in both time domain and frequency domain. The presented approach allows for the simulation of complex reflection and scattering phenomena using a very small number of degrees of freedom while the mesh consists of one-dimensional elements only. KW - Scaled Boundary Finite Element Method KW - Guided waves KW - Unbounded domains KW - Cracks PY - 2015 DO - https://doi.org/10.1016/j.jcp.2015.04.032 SN - 0021-9991 SN - 1090-2716 VL - 295 SP - 438 EP - 455 PB - Elsevier Inc. CY - Amsterdam AN - OPUS4-33207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, C. A1 - Birk, C. T1 - Numerical modeling of waveguides embedded in infinite media T2 - ICSV22 - 22nd International congress on sound and vibration (Proceedings) N2 - This paper presents recently developed approaches for the numerical simulation of guided elastic waves in structures that are embedded in infinite fluid or solid media. The waveguide is described by the Scaled Boundary Finite Element Method, which is a general semi-analytical method that requires discretization of the boundary only. The influence of the surrounding medium on the wave propagation inside the waveguide is accounted for by appropriate boundary conditions. It is demonstrated that for many practical applications a formulation based on simple dashpot boundary conditions yields sufficiently accurate results. To increase accuracy for fluids, an alternative formulation based on exact boundary conditions and inverse iteration is proposed. This approach is of use particularly if the acoustic properties of the waveguide and surrounding material are similar. T2 - ICSV22 - 22nd International congress on sound and vibration CY - Florence, Italy DA - 12.07.2015 PY - 2015 SN - 978-88-88942-48-3 SN - 2329-3675 SP - 1 EP - 5 AN - OPUS4-33829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bause, F. A1 - Gravenkamp, Hauke A1 - Rautenberg, J. A1 - Henning, B. T1 - Transient modeling of ultrasonic guided waves in circular viscoelastic waveguides for inverse material characterization JF - Measurement science and technology N2 - In this contribution, we present an efficient approach for the transient and time-causal modeling of guided waves in viscoelastic cylindrical waveguides in the context of ultrasonic material characterization. We use the scaled boundary finite element method (SBFEM) for efficient computation of the phase velocity dispersion. Regarding the viscoelastic behavior of the materials under consideration, we propose a decomposition approach that considers the real-valued frequency dependence of the (visco-)elastic moduli and, separately, of their attenuation. The modal expansion approach is utilized to take the transmitting and receiving transducers into account and to propagate the excited waveguide modes through a waveguide of finite length. The effectiveness of the proposed simulation model is shown by comparison with a standard transient FEM simulation as well as simulation results based on the exact solution of the complex-valued viscoelastic guided wave problem. Two material models are discussed, namely the fractional Zener model and the anti-Zener model; we re-interpret the latter in terms of the Rayleigh damping model. Measurements are taken on a polypropylene sample and the proposed transient simulation model is used for inverse material characterization. The extracted material properties may then be used in computer-aided design of ultrasonic systems. KW - Viscoelasticity KW - Ultrasonics KW - Guided waves KW - Inverse problem KW - Scaled boundary finite KW - Element method PY - 2015 DO - https://doi.org/10.1088/0957-0233/26/9/095602 SN - 0957-0233 SN - 1361-6501 VL - 26 IS - 9 SP - 095602-1 EP - 095602-17 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-33830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke T1 - Die Scaled Boundary Finitie Element Method zur Simultaion von Ultraschallwellen T2 - Seminar für Numerische Mathematik und Mechanik, Universität Duisburg-Essen T2 - Seminar für Numerische Mathematik und Mechanik, Universität Duisburg-Essen CY - Essen DA - 2015-06-29 PY - 2015 AN - OPUS4-33566 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, Ch. T1 - Modeling wave propagation in large structures using the Scaled Boundarx Finite Element Method T2 - 13th US National Congress on Computational Mechanics T2 - 13th US National Congress on Computational Mechanics CY - San Diego (USA) DA - 2015-07-26 PY - 2015 AN - OPUS4-33785 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gravenkamp, Hauke A1 - Song, Ch. A1 - Nararajan, S. A1 - Talebi, H. A1 - Saputra, A. A1 - Ooi, E. T. T1 - A Semi-analytical Displacement Based Formulation of Arbitrary Polyhedral Elements T2 - 13th US National Congress on Computational Mechanics T2 - 13th US National Congress on Computational Mechanics CY - San Diego (USA) DA - 2015-07-26 PY - 2015 AN - OPUS4-33786 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krome, Fabian A1 - Gravenkamp, Hauke T1 - 3-D Waveguide modeling and simulation using SBFEM T2 - ICSV22 PROCEEDINGS N2 - The modeling of waveguides by means of the Scaled Boundary Finite Element Method (SBFEM) has recently been addressed and is considered an effective procedure for the simulation of ultrasonic guided waves in plates and uniform structures, as well as their interaction with defects. This work presents the extension of the known applications like uniform concrete foundation cylinders to structures with more complex shapes and defects. The main focus is the required modeling of 3-D structures in SBFEM to solve these efficiently. Furthermore the coupling of different models is discussed. This involves models like a mainly uniform foundation cylinder with varying material behavior or geometry in certain areas which has to be modeled in 3-D SBFEM. With the presentation of numerical examples the accuracy and performance of the modeling is discussed and the advantages in improving numerical stability are shown. T2 - ICSV22 CY - Florence, Italy DA - 12.07.2015 KW - Scaled boundary finite element method PY - 2015 SP - 2805 EP - 2810 AN - OPUS4-43416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano, Daniel A1 - Bulling, Jannis A1 - Gravenkamp, Hauke A1 - Birk, Carolin T1 - Domain decoupling implementation for efficient ultrasonic wave simulations using scaled boundary finite elements and the mortar method JF - Computer Methods in Applied Mechanics and Engineering N2 - We introduce a novel approach that combines the scaled boundary finite element method (SBFEM) with a mortar coupling to enhance the computational modelling of elastic wave propagation and interaction with local features in the ultrasonic range. The key objective is to achieve decoupling between different regions of interest, enabling independent meshes for the zones where waves either propagate or interact with localised discontinuities in the elastic media. This decoupling allows us to exploit the benefits offered by various SBFEM formulations. Thus, we can select the most suitable solution for each specific region. An important concept we emphasise is the differentiation between the near field and far field regions. The near field encompasses zones where the precise representation of small features compared to the wavelength is crucial. At the same time, the far field comprises homogeneous regions where the waves propagate without interactions, eventually radiating towards infinity if the domain is unbounded. By separating these two zones, we can improve the computational performance by employing finer discretisation only where necessary. Furthermore, this decoupling enables the reuse of far field models in parametric analyses, making it highly valuable for scenarios focused particularly on local elastic wave interactions. This approach offers considerable potential in such cases. The modelling technique is validated, and its potential is demonstrated through practical applications. KW - Computer Science Applications KW - General Physics and Astronomy KW - Mechanical Engineering KW - Mechanics of Materials KW - Computational Mechanics PY - 2023 DO - https://doi.org/10.1016/j.cma.2023.116465 SN - 0045-7825 VL - 417 IS - Part A SP - 1 EP - 21 PB - Elsevier BV AN - OPUS4-58478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lozano, Daniel A1 - Bulling, Jannis A1 - Gravenkamp, Hauke A1 - Prager, Jens A1 - Birk, Carolin T1 - The SBFEM to simulate the scattering of ultrasonic guided waves interacting with defects in plate structures N2 - In the field of guided waves for non-destructive testing, the interaction of these waves with damages or other discontinuities in a structure is critical. When a guided wave mode travels and hits a defect, it scatters in all directions, converting to other modes and reflecting the existing one. These interactions are captured in scattered far field complex amplitudes. The amplitudes are stored in scattering matrices, which characterise the elastodynamic behaviour of a defect completely. Scattering matrices are also useful to simulate backpropagation from a defect using ray-tracing methods. Simulating these interactions is challenging, and analytical solutions only exist for simple geometries. Still, using general tools like the finite element method results in large, usually costly models. Recently, researchers proposed a method based on a numerical implementation of the Kirchhoff–Helmholtz integral that allows the computation of the scattering matrices using a model containing only the damaged region. However, classical methods to resolve the far field and low-order elements were used, leading to large models yet more efficient than using other techniques. We propose using the SBFEM as an alternative to enhance the computation of the far field scattering. The damaged region is discretised using high-order polyhedral elements, while the far field is constructed using a modified version of the SBFEM. Examples compared to the literature demonstrate the validity of the approach. T2 - Doktorandentreffen CY - Attendorn, Germany DA - 16.10.2023 KW - SBFEM KW - Guided Waves KW - Scattering PY - 2023 AN - OPUS4-59775 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -