Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-1062 Zeitschriftenartikel Bovtun, Viktor Petrovic; Stark, Wolfgang; Kelm, Jürgen; Porokhonskyy, V.; Yakimenko, Y. Microwave Dielectric Properties of Rubber Compounds Undergoing Vulcanisation - Part 1. Natural rubber with and without carbon black filler Heidelberg Hüthig Deutsche Kautschuk-Gesellschaft 2000 Kautschuk, Gummi, Kunststoffe (KGK) 2016-02-19 OPUS4-7273 Zeitschriftenartikel Bovtun, Viktor Petrovic; Stark, Wolfgang; Kelm, Jürgen; Pashkov, V.M.; Yakimenko, Y. Characterization of carbon black filled rubber compounds by the Microwave Coaxial Method München Carl Hanser Verlag Bundesanstalt für Materialforschung und -prüfung 2005 Materialprüfung = Materials testing 47 3 118 122 2016-02-19 OPUS4-27880 Zeitschriftenartikel Bovtun, Viktor Petrovic; Döring, Joachim; Bartusch, Jürgen; Gaal, Mate; Erhard, Anton; Kreutzbruck, Marc; Yakymenko, Y. Enhanced electromechanical response of ferroelectret ultrasonic transducers under high voltage excitation Polypropylene based ferroelectret films exhibit a strong electromechanical activity and provide a promising solution for the air coupled ultrasonic (ACUS) transducers. Ultrasonic transmission between two air coupled ferroelectret transducers in dependence on the amplitude and polarity of the high voltage exciting pulse revealed a strongly non-linear electromechanical response of the ferroelectret transmitter which provides an increase in the transmitter efficiency. The authors present a simple model describing both promotion and competition of the piezoelectric and electrostriction contributions, as well as increase in the transducer constant under high voltage excitation. Enlargement of the inverse transducer constant of the polypropylene ferroelectret film by a factor of 4 was demonstrated. The non-linear properties of the polypropylene ferroelectrets result in a strong increase in their ACUS figure of merit under the high voltage excitation, which exceeds the results of their technological optimisation. Consequently, enhancement of the ACUS system transmission by 12 dB and signal to noise ratio by 32 dB was achieved. London Maney 2013 Advances in applied ceramics 112 2 97 102 10.1179/1743676112Y.0000000021 2016-02-20 OPUS4-27778 Zeitschriftenartikel Döring, Joachim; Bartusch, Jürgen; Gaal, Mate; Kreutzbruck, Marc; Erhard, Anton; Bovtun, Viktor Petrovic Ferroelektret-Prüfköpfe für die zerstörungsfreie Prüfung mit Luftultraschall Für die luftgekoppelte Ultraschall-Prüfung wird der Prototyp eines neuartigen Prüfkopfes vorgestellt. Statt eines piezokeramischen Ultraschall-Wandlers mit einer λ/4-Anpassschicht wird eine Ferroelektret-Folie aus schaumförmigem Polypropylen eingesetzt. Durch die außerordentlich geringe akustische Impedanz der Folie reduzieren sich die Reflexionsverluste an den Grenzschichten zur Luft so stark, dass bei diesem Prüfkopf auf eine λ/4-Anpassschicht verzichtet werden kann. Außerdem ist die Folie hochspannungsfest. Sie konnte mit Spannungen von mehr als 3500 V angesteuert werden und erlaubte eine Vorspannung am Ultraschall-Wandler des Empfangsprüfkopfes von 2000 V. Mithilfe der hohen Anregungsspannung stieg die Amplitude des akustischen Prüfimpulses auf das 11,2-Fache. Die Empfindlichkeit des Empfängers erhöhte sich durch die Vorspannung weiter um den Faktor 4,3. Insgesamt steigt die Amplitude am Empfänger also auf das 48-Fache, bei gleichbleibendem Rauschpegel. Ein abschließender Vergleich mit kommerziellen Luftultraschall-Prüfköpfen belegt die Überlegenheit der Folien-Prüfköpfe. Damit rückt der Einsatz einer vollwertigen Impuls-Echo-Technik auch bei der luftgekoppelten Ultraschallprüfung deutlich näher. München Hanser Bundesanstalt für Materialforschung und -prüfung 2013 Materials testing 55 2 96 102 2016-02-20 OPUS4-15074 Zeitschriftenartikel Bovtun, Viktor Petrovic; Döring, Joachim; Bartusch, Jürgen; Beck, Uwe; Erhard, Anton; Yakymenko, Y. Ferroelectret non-contact ultrasonic transducers Dielectric and electromechanical properties of the cellular polypropylene ferroelectret films (EMFIT), combining strong piezoelectric response with a low density and softness, evidence their high potential for the air-coupled ultrasonic applications. The disadvantage of the low coupling factor is compensated by the extremely low acoustic impedance, which provides excellent matching to air and promises efficient sound transmission through the air–transducer interface. The influence of the electrodes on the electromechanical properties was investigated. Electron beam evaporation technology was adapted to the EMFIT films, and films with both-sided Au and Al electrodes were prepared without reducing or suppressing of the electromechanical properties. Finally, prototype transducers based on the EMFIT films were developed. In spite of the simple construction and absence of matching layers, high sensitivity of the EMFIT transducers was proved in the air-coupled ultrasonic experiment. Amplitude and delay time scanned images of the polyethylene step wedge with holes, obtained in both pulse-echo and transmission modes, demonstrate that non-contact ultrasonic imaging and testing with EMFIT transducers is possible. Berlin Springer 2007 Applied physics A 88 4 737 743 2016-02-19 OPUS4-14211 Beitrag zu einem Tagungsband Bovtun, Viktor Petrovic; Döring, Joachim; Bartusch, Jürgen; Beck, Uwe; Erhard, Anton; Yakimenko, Y. EMFIT Ferroelectret Film Transducers for Non-Contact Ultrasonic Testing Berlin European Federation for Non-Destructive Testing Deutsche Gesellschaft für zerstörungsfreie Prüfung 2006 9th European Conference on NDT 3-931381-86-2 9th European Conference on NDT Berlin, Germany 2006-09-25 2006-09-29 1 10(?) 2016-02-19 OPUS4-21809 Zeitschriftenartikel Döring, Joachim; Bovtun, Viktor Petrovic; Bartusch, Jürgen; Erhard, Anton; Kreutzbruck, Marc; Yakymenko, Y. Nonlinear electromechanical response of the ferroelectret ultrasonic transducers The ultrasonic transmission between two air-coupled polypropylene (PP) ferroelectret (FE) transducers in dependence on the amplitude of the high-voltage exciting pulse revealed a strongly nonlinear electromechanical response of the FE transmitter. This phenomenon is described by a linear increase of the inverse electromechanical transducer constant t33(1) of the PP FE film with an increase of the exciting electrical pulse amplitude. Enlargement of t33(1) by a factor of 4 was achieved by application of 3500 V exciting pulses. The electrostriction contribution to t33(1) can be attributed to the electrostatic force between electrodes and the Maxwell stress effect. The nonlinear electromechanical properties of the PP FE result in a strong increase of its air-coupled ultrasonic (ACUS) figure of merit (FOM) under the high-voltage excitation, which exceeds results of the PP FE technological optimization. The FOM increase can be related to the increase of PP FE coupling factor and/or to the decrease of its acoustic impedance. A significant enhancement of the ACUS system transmission (12 dB) and signal-to-noise ratio (32 dB) was demonstrated by the increase of excitation voltage up to 3500 V. The nonlinear electromechanical properties of the PP FEs seem to be very important for their future applications. Berlin Springer 2010 Applied physics A 100 2 479 485 10.1007/s00339-010-5752-7 2016-02-19 OPUS4-20924 Zeitschriftenartikel Bovtun, Viktor Petrovic; Döring, Joachim; Wegener, M.; Bartusch, Jürgen; Beck, Uwe; Erhard, Anton; Borisov, V. Air-coupled ultrasonic applications of ferroelectrets New York, NY Taylor & Francis 2008 Ferroelectrics 370 1 11 17 10.1080/00150190802380243 2016-02-19 OPUS4-26405 Beitrag zu einem Tagungsband Gaal, Mate; Döring, Joachim; Bartusch, Jürgen; Beck, Uwe; Weise, Matthias; Bovtun, Viktor Petrovic; Brekow, Gerhard; Kreutzbruck, Marc Parameter reproducibility of polypropylene ferroelectret transducers for air-coupled ultrasonic testing The extremely low acoustic impedance of polypropylene ferroelectret combined with its piezoelectric properties makes this material suitable for construction of aircoupled ultrasonic transducers for non-destructive testing. For the fabrication of transducers with a stable quality, the reproducibility of their key parameters is of interest. The reproducibility was evaluated by means of (i) impedance spectroscopy and (ii) pulse-echo measurements. (i) Impedance spectroscopy was applied to identify the resonance frequency, the coupling factor and the acoustic impedance of several nominally identical transducers. (ii) Pulse-echo measurements yielded the signal form of these transducers. The variation of the signal amplitude measured with pulseecho technique was about 10 dB. A part of this variation Comes from the deposition of transducer electrodes and another part from local variations of ferroelectret properties. The variation of the signal amplitude was caused by the observed variation of the coupling factor, which was also about 10 dB. The variation of the acoustic impedance was only about 1 dB, thus having no effect on the variation of the signal amplitude. These results indicate that the variability can be reduced by improving the control of electrode deposition and by optimizing the production technology affecting the reproducibility of material properties. Institute of Electrical and Electronics Engineers (IEEE) 2011 IUS 2011 - IEEE International ultrasonics symposium 2011 IEEE International ultrasonics symposium (IUS) Orlando, FL, USA 18.10.2011 21.10.2011 Abstract-ID 258 1 3 2016-02-19 OPUS4-35956 Zeitschriftenartikel Gaal, Mate; Bovtun, Viktor; Stark, Wolfgang; Erhard, Anton; Yakymenko, Y.; Kreutzbruck, Marc Viscoelastic properties of cellular polypropylene ferroelectrets Viscoelastic properties of cellular polypropylene ferroelectrets (PP FEs) were studied at low frequencies (0.3-33 Hz) by dynamic mechanical analysis and at high frequencies (250 kHz) by laser Doppler vibrometry. Relaxation behavior of the in-plane Young's modulus (Y´ 11~1500 MPa at room temperature) was observed and attributed to the viscoelastic response of polypropylene matrix. The out-of-plane Young's modulus is very small (Y´33≈0.1 MPa) at low frequencies, frequency- and stress-dependent, evidencing nonlinear viscoelastic response of PP FEs. The highfrequency mechanical response of PP FEs is shown to be linear viscoelastic with Y´33≈0.8 MPa. It is described by thickness vibration mode and modeled as a damped harmonic oscillator with one degree of freedom. Frequency dependence of Y*33 in the large dynamic strain regime is described by the broad Cole-Cole relaxation with a mean frequency in kHz range attributed to the Dynamics of the air flow between partially closed air-filled voids in PP FEs. Switching-off the relaxation contribution causes dynamic crossover from the nonlinear viscoelastic regime at low frequencies to the linear viscoelastic regime at high frequencies. In the small strain regime, contribution of the air flow seems to be insignificant and the power-law response, attributed to the mechanics of polypropylene cell walls and closed air voids, dominates in a broad frequency range. Mechanical Relaxation caused by the air flow mechanism takes place in the sound and ultrasound frequency range (10 Hz-1MHz) and, therefore, should be taken into account in ultrasonic applications of the PP FEs deal with strong exciting or receiving signals. AIP Publishing 2016 Journal of Applied Physics 119 Article Number: 125101 10.1063/1.4944798 2016-05-10 OPUS4-19059 Beitrag zu einem Tagungsband Döring, Joachim; Bovtun, Viktor Petrovic; Bartusch, Jürgen; Erhard, Anton Eigenschaften von Polypropylen- und PVDF-Folien für Luftschall-Anwendungen An Methoden zur luftgekoppelten Ultraschallprüfung wird seit einigen Jahren mit großer Intensität gearbeitet. Probleme bei der praktischen Realisierung entstehen vor allem durch die großen Unterschiede in der akustischen Impedanz von Wandlermaterial und Luft. Sie führen zu erheblichen Signaldämpfungen. Durch die Verwendung von Kunststoff-Folien z.B. aus porösem Polypropylen kann dieser Unterschied stark reduziert werden. Im Beitrag werden die akustischen Eigenschaften dieser Folien untersucht und im Hinblick auf ihre Eignung für die Luftultraschall-Technik analysiert. Salzburg, Österreich Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) 2004 DACH-Jahrestagung 2004 - ZfP in Forschung, Entwicklung und Anwendung DACH-Jahrestagung 2004 - ZfP in Forschung, Entwicklung und Anwendung Salzburg, Österreich 2004-05-17 2004-05-19 1 4 2016-02-19