TY - CONF A1 - Gaal, Mate A1 - Bartusch, Jürgen A1 - Döring, Joachim A1 - Dohse, Elmar A1 - Lange, Thorid A1 - Hillger, W. A1 - Kreutzbruck, Marc T1 - Air-coupled ferroelectret ultrasonic transducers applied to testing of fiber-reinforced polymers T2 - 12th International conference of the Slovenian society for non-destructive testing - Application of contemporary non-destructive testing in engineering (Proceedings) T2 - 12th International conference of the Slovenian society for non-destructive testing - Application of contemporary non-destructive testing in engineering CY - Portoroz, Slovenia DA - 2013-09-04 KW - Air-coupled ultrasound KW - Transducer KW - Ferroelectret KW - Cellular polypropylene KW - Fiber-reinforced polymers PY - 2013 SN - 978-961-93537-0-7 SP - 43 EP - 50 AN - OPUS4-29927 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Daschewski, Maxim A1 - Boehm, Rainer A1 - Prager, Jens A1 - Kreutzbruck, Marc A1 - Harrer, Andrea T1 - Physics of thermo-acoustic sound generation JF - Journal of applied physics N2 - We present a generalized analytical model of thermo-acoustic sound generation based on the analysis of thermally induced energy density fluctuations and their propagation into the adjacent matter. The model provides exact analytical prediction of the sound pressure generated in fluids and solids; consequently, it can be applied to arbitrary thermal power sources such as thermophones, plasma firings, laser beams, and chemical reactions. Unlike existing approaches, our description also includes acoustic near-field effects and sound-field attenuation. Analytical results are compared with measurements of sound pressures generated by thermo-acoustic transducers in air for frequencies up to 1 MHz. The tested transducers consist of titanium and indium tin oxide coatings on quartz glass and polycarbonate substrates. The model reveals that thermo-acoustic efficiency increases linearly with the supplied thermal power and quadratically with thermal excitation frequency. Comparison of the efficiency of our thermo-acoustic transducers with those of piezoelectric-based airborne ultrasound transducers using impulse excitation showed comparable sound pressure values. The present results show that thermo-acoustic transducers can be applied as broadband, non-resonant, high-performance ultrasound sources. KW - Thermophone KW - Ionophone KW - Thermo-acoustic effect KW - Non resonant ultrasound source PY - 2013 DO - https://doi.org/10.1063/1.4821121 SN - 0021-8979 SN - 1089-7550 VL - 114 SP - 114903-1 - 114903-12 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-29278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prager, Jens A1 - Kitze, Jessica A1 - Acheroy, Cécile A1 - Brackrock, Daniel A1 - Brekow, Gerhard A1 - Kreutzbruck, Marc T1 - SAFT and TOFD - A comparative study of two defect sizing techniques on a reactor pressure vessel mock-up JF - Journal of nondestructive evaluation N2 - Defect sizing is required for a quantitative assessment of the quality and reliability of safety relevant components and materials using ultrasonic non-destructive testing. The SAFT (Synthetic Aperture Focussing Technique) and the TOFD technique (Time Of Flight Diffraction) are such promising sizing candidates, extracting more information from the raw ultrasound echo data and the corresponding crack tip response. In this work the phased array technique is used to inspect a clad mock-up model of a pressure vessel section. The full scale model contains artificial test reflectors which are located in the weld and in the cladding region as well. The defects—representing typical flaws at a very early stage—are analysed with different frequencies, beam angles and directions of incidence. For the reconstruction of reflector indications a SAFT algorithm is applied to the phased array measurement results. Additionally the reflectors are analysed by means of the TOFD technique, using different beam angles at the same time. Both analysis methods are performed using different directions of incidence considering the complex cladding structure underneath the inner surface of the mock-up model. A direct comparison of the SAFT and TOFD techniques shows that, besides the clarity of the results, the detection and sizing capabilities of SAFT are far better. KW - Ultrasonic inspection KW - Phased array probe KW - Synthetic aperture focussing technique KW - Time of flight diffraction method PY - 2013 DO - https://doi.org/10.1007/s10921-012-0153-9 SN - 0195-9298 SN - 1573-4862 VL - 32 IS - 1 SP - 1 EP - 13 PB - Plenum Press CY - New York, NY AN - OPUS4-29277 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc A1 - Pelkner, Matthias A1 - Gaal, Mate A1 - Daschewski, Maxim A1 - Brackrock, Daniel T1 - Evolution of modern NDT-methods for the inspection of lightweight components T2 - 12th International conference of the Slovenian society for non-destructive testing - Application of contemporary non-destructive testing in engineering (Proceedings) N2 - NDT is a multidisciplinary research area fusing the disciplines of natural Science and engineering. Particularly in the early development stages of a new testing method, feasibility investigations focus on the fundamental physical interaction between the sensing mechanism and specimen. Research activities during subsequent phases of modular prototype development, technical System Integration and Validation primarily attempt to solve the practical engineering and real-life aspects of a testing method. We show several examples of new methods in different stages of development and highlight the potential for further industrial use. The first section deals with Steel surfaces of lightweight components which are inspected with pm-sized magneto resistive sensor arrays. This quantitative magnetic stray field approach combines high spatial resolution and very high sensitivity, enabling the user to detect even very small micro-defects. Tuming to CFRP components we also show new developments in airbome ultrasonic testing. Here we use ferroelectret foils to reduce the acoustical mismatch between transducer and air, which enhances the signal-to-noise ratio. A further example illuminates the use of metallic nano layers as a broadband thermo acoustical emitter. Their use provides both high sound pressures and very broadband Signal characteristics. When it comes to CFRP components and other anisotropic and highly Scattering materials, ultrasonic matrix arrays in conjunction with many angles of incidences per transducer position can help to enhance the statistics of a testing problem. In the field of conventional water-coupled UT testing we also show the use of matrix array transducers providing a tomographic-like 3D-image of impact damage in CFRP samples. T2 - 12th International conference of the Slovenian society for non-destructive testing - Application of contemporary non-destructive testing in engineering CY - Portoroz, Slovenia DA - 04.09.2013 KW - GMR-sensors arrays KW - Air coupled ultrasonics KW - Thermo acoustical transducers KW - Matrix arrays PY - 2013 SN - 978-961-93537-0-7 SP - 303 EP - 314 AN - OPUS4-29245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc A1 - Gaal, Mate A1 - Bartusch, Jürgen A1 - Döring, Joachim A1 - Dohse, Elmar A1 - Lange, Thorid A1 - Hillger, W. T1 - Air-Coupled Ferroelectret Ultrasonic Transducers Applied to Testing of Fiber-Reinforced Polymers T2 - The 12th International Conference of the Slovenian Society for Non-Destructive Testing >>Application of Contemporary Non-Destructive Testing in Engineering<< ICNDT T2 - The 12th International Conference of the Slovenian Society for Non-Destructive Testing >>Application of Contemporary Non-Destructive Testing in Engineering<< ICNDT CY - Portorož, Slovenia DA - 2013-09-04 PY - 2013 AN - OPUS4-29196 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc T1 - Moderne bildgebende Verfahren in der zerstörungsfreien Prüfung zur Inspektion von Leichtbaukomponenten und metallischen Oberflächen T2 - DGZFP-Arbeitskreis München T2 - DGZFP-Arbeitskreis München CY - Munich, Germany DA - 2013-09-19 PY - 2013 AN - OPUS4-29160 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc T1 - Evolution of Modern Sensor/Actor Technologies for the Inspection of Lightweight Components T2 - ICNDT T2 - ICNDT CY - Portorož, Slovenia DA - 2013-09-05 PY - 2013 AN - OPUS4-29158 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc T1 - Non-destructive testing of spot welds using transient heat flows T2 - IIW-Tagung T2 - IIW-Tagung CY - Essen, Germany DA - 2013-09-13 PY - 2013 AN - OPUS4-29157 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc T1 - Magnetic Detection of Surface Breaking Cracks Using GMR-Sensor Arrays T2 - IIW-Tagung T2 - IIW-Tagung CY - Essen, Germany DA - 2013-09-13 PY - 2013 AN - OPUS4-29156 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kreutzbruck, Marc T1 - Automated Inspection of Surface Breaking Cracks Using GMR-Sensor Arrays T2 - ISEM 2013 T2 - ISEM 2013 CY - Quebec City, Canada DA - 2013-08-01 PY - 2013 AN - OPUS4-29154 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -