TY - CONF A1 - Gaal, Mate A1 - Ahmadzadeh, M. A1 - Hufschläger, Daniel T1 - Sound field measurements on thermoacoustic air-coupled transducers N2 - There are many different methods to characterize air-coupled ultrasonic transducers for non-destructive testing. Data sheets of various manufacturers contain information about some parameters important for the performance of transducers, but this information is not standardized, so that a comparison between probes of different manufacturers is difficult. Therefore, the German Society for Non-Destructive Testing (DGZfP) is working on a guideline to characterization of air-coupled probes. One of the topics in this guideline is the application of thermoacoustic transducers for the characterization of receivers and another topic is the application of microphones for the characterization of transmitters. In this presentation we compare various characterization methods with the particular focus on the characterization of thermoacoustic transducers using an optical microphone. Both thermoacoustic transmitters and optical microphones have a very large bandwidth compared to conventional air-coupled transducers, but their spectrum is not entirely linear, which needs to be taken into account if they are applied as reference transducers. T2 - JSNDI online workshop “Emerging Technologies of Advanced Ultrasonic Measurement” CY - Online meeting DA - 14.12.2021 KW - Air-coupled ultrasound KW - Transducer KW - Sound field PY - 2021 AN - OPUS4-54195 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völz, Uwe A1 - Kreutzbruck, Marc A1 - Heckel, Thomas A1 - Mrasek, Heinz T1 - Verification of ultrasonic field modeling by visualization of wave propagation in solids N2 - When dealing in ultrasonic testing with inhomogeneous and anisotropic material structure such as diverse types of components made from austenitic or nickel based cast, which are currently used for modern power plant concepts, data interpretation is quite difficult. For better understanding of the complex interaction between the sound field and the component under test, the mathematical modeling of sound propagation in solids is a substantial task to increase the probability of detection of relevant defects. First we present a mathematical approach for modeling the three dimensional transient particle displacement as a function of time in each point in a half space excited by an impulsive point load at the surface. The transient ultrasonic field of a rectangular array element is calculated with this approach by a point source synthesis. Based on this solution we model the wave propagation of a phased array transducer by time delayed superposition of the wave field of the transducer elements. Next we use an electrodynamic technique to visualize the grazing sound field at the surface of a test block radiated by a phased array probe. By detecting the grazing beam at the sample’s surface with a small electrodynamic probe, we measured the particle displacement as a function of time. It allows for measuring the displacement in all three spatial directions. This comprises the detection of the horizontal and vertical particle displacement with respect to the surface and thus also the detection of longitudinal and shear waves is possible. The calculated and measured wave fields will be compared for different delay laws in isotropic and transversely isotropic media. The results support the theoretical activities to model the wave propagation and to find optimal testing parameters for different components and configurations. T2 - 8th International conference on NDE in relation to structural integrity for nuclear and pressurised components CY - Berlin, Germany DA - 2010-09-29 KW - Sound field KW - Wave propagation KW - Visualization KW - Modeling KW - Phased array PY - 2010 SN - 978-3-940283-30-6 IS - DGZfP-BB 125 (Th.4.A.2) SP - 1 EP - 7 CY - Berlin AN - OPUS4-25229 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völz, Uwe A1 - Mrasek, Heinz A1 - Matthies, Klaus A1 - Kreutzbruck, Marc T1 - Visualization of sound propagation with electrodynamic probes N2 - When dealing in ultrasonic testing with inhomogeneous material structure data interpretation can be rather difficult. This is especially the case when using anisotropic dissimilar welds made from austenitic steel or nickel based alloys, which are currently used for modern power plant concepts. For better understanding of the complex interaction between the sound field and the component under test, the visualization of sound propagation in solids is a substantial task to increase the probability of detection of relevant defects. However, there exist only a small number of appropriate techniques published today, such as scanning laser interferometer, piezoelectric and optical approaches in case of transparent solids. In this work we present an electrodynamic technique providing a simple use and a high signal to noise ratio. By detecting the grazing beam with an electrodynamic probe with a size smaller than 10 mm, we measured the particle displacement as a function of time with a spatial resolution in the order of 1 mm. Adapting the electrodynamic probe and its coil alignment allows for measuring the displacement components in all three dimensions. This comprises the detection of the horizontal and vertical particle displacement with respect to the surface and thus also the transformation from longitudinal waves into transversal waves and vice versa is possible. A SNR of higher than 36 dB could be achieved within ferromagnetic and high conductive chrome steel when using a transversal wave generated by an angled beam transducer. We report on measurements of the sound field in complex weld joints. One example shows a 10 mm thick narrowgap weld joining a nickel alloy with a chrome steel yielding a substantial anisotropy of the weld structure. The test system enables us to visualize the wave propagation within the weld and indicates the reflection scenario and the energy losses due to both the anisotropic structure and material defects. T2 - ECNDT 2010 - 10th European conference on non-destructive testing CY - Moscow, Russia DA - 2010-06-07 KW - Ultrasonic KW - Sound field KW - Visualization KW - Electrodynamic probe KW - Nondestructive testing (NDT) KW - Nickel alloy KW - Anisotropic weld KW - Narrow-gap weld PY - 2010 SN - 978-1-617-82791-4 SP - 1 EP - 8 AN - OPUS4-22974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Völz, Uwe A1 - Mrasek, Heinz A1 - Matthies, Klaus A1 - Kreutzbruck, Marc ED - Mazal, Pavel T1 - Visualization of sound propagation with electrodynamic probes T2 - 5th International workshop of NDT experts - NDT in progress 2009 CY - Prague, Czech Republic DA - 2009-10-12 KW - Ultrasonic KW - Sound field KW - Visualization KW - Electrodynamic probe KW - Nondestructive testing (NDT) KW - Nickel alloy KW - Anisotropic weld KW - Narrow-gap weld PY - 2009 SN - 978-80-214-3968-9 SP - 321 EP - 328 AN - OPUS4-20334 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Völz, Uwe A1 - Mrasek, Heinz A1 - Matthies, Klaus A1 - Wüstenberg, Hermann A1 - Kreutzbruck, Marc ED - Thompson, D. O. ED - Chimenti, D. E. T1 - Electrodynamic approach for visualization of sound propagation in solids N2 - The visualization of sound propagation in solids is vital for transducer adaptation and better understanding of complex test samples and their wave propagation modeling. In this work we present an electrodynamic technique detecting the grazing sound beam with a 10 mm-sized electrodynamic probe. The particle displacement along the sample’s surface was then measured as a function of time and position. Adapting the electrodynamic probe and its coil alignment allows for measuring the displacement components in all three dimensions. Thus horizontal and vertical particle displacement with respect to the surface can be detected. A SNR of up to 40 dB could be achieved within ferromagnetic and high conductive chrome steel when using a shear wave generated by an angle beam probe. When dealing with nonconductive materials such as PMMA we obtained a reduced SNR of 12 dB. We report on measurements of the sound field in complex weld joints. One example shows a narrow gap weld joining a nickel alloy with a chrome steel. The weld of the 80 mm-thick test block shows a distinct anisotropic texture. The system enables us to visualize the wave propagation within the weld and indicates the reflection and scattering scenario and the energy losses due to both the anisotropic structure and material defects. T2 - 35th Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Chicago, IL, USA DA - 2008-07-20 KW - Ultrasonic KW - Sound field KW - Visualization KW - Electrodynamic probe KW - Nondestructive testing KW - Nickel alloy KW - Anisotropic weld KW - Narrow gap weld PY - 2009 SN - 978-0-7354-0629-2 SN - 0743-0760 SN - 0094-243X N1 - Serientitel: AIP conference proceedings – Series title: AIP conference proceedings IS - 1096 SP - 758 EP - 765 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-19436 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -