TY - CONF A1 - Wolf, Julia A1 - Mielentz, Frank T1 - Grundlagenuntersuchungen von neuartigen US-Sensoren in Beton T2 - 73. Jahrestagung der Deutschen Geophysikalischen Gesellschaft (DGG) CY - Leipzig, Germany DA - 2013-03-04 PY - 2013 AN - OPUS4-27863 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolf, Julia A1 - Milmann, Boris A1 - Helmerich, Rosemarie A1 - Köpp, Christian A1 - Mielentz, Frank A1 - Wiggenhauser, Herbert A1 - Kurz, J.H. A1 - Moryson, R.-M. A1 - Samokrutov, A. A1 - Alekhin, S. G. A1 - Alver, Ninel A1 - Sazak, H.-Ö. ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Ultrasound based monitoring system for concrete monolithic objects N2 - Ultrasound sensors should be embedded into concrete for monitoring concrete properties. These new longitudinal wave sensors with a center frequency of 60 kHz were examined regarding their suitability for ultrasonic measurements in concrete structures in terms of emission characteristics, sensitivity and frequency ränge. For the measurement of the radiation patterns, the sensors were embedded vertically and horizontally in concrete cylinders. The directivity pattern was measured using a laser vibrometer. The sensitivity of the sensor was determined in water using different sensors of the same type. It shows changes in the signal amplitude as well as variations in the frequency ränge for different transmitter-receiver combinations. The attenuation of the concrete affects the achievable resolution of the measurements and thus, the maximum possible spacing of the sensors within a concrete element. Experimental tests helped optimizing the distances with respect to the required resolution and the effort of embedding the sensors. The signal attenuation in the concrete was measured in the frequency ränge of 60 kHz in response to various degrees of reinforcement and grain size. For this purpose, the sensors were cast at different distances in the specimens studied. The recorded Signals were evaluated for their amplitude and frequency spectrum. T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 09.12.2013 KW - Ultrasound KW - Concrete KW - Monitoring system KW - Ultrasonic network KW - Embedded sensor PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 6 AN - OPUS4-29642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Milmann, Boris A1 - Wiggenhauser, Herbert T1 - Grundlagenuntersuchungen von Ultraschall-Sensoren in Beton N2 - Für Ultraschallmessungen in Betonbauteilen wurden neuartige radialsymmetrisch abstrahlende Longitudinalwellenprüfköpfe mit einer Mittenfrequenz von 60 kHz auf deren Eignung hinsichtlich Abstrahlcharakteristik, Empfindlichkeit und Frequenzspektrum untersucht. Für die Messung der Abstrahlcharakteristiken wurden die Prüfköpfe vertikal und horizontal in Betonzylinder eingebettet und die Richtungsabhängigkeiten der Schallschnelle mithilfe eines Laservibrometers gemessen. Die Streuung der Prüfkopfempfindlichkeit wurde im Wasserbad unter Verwendung verschiedener Köpfe gleicher Bauart bestimmt. Außer Änderungen der Signalamplituden zeigten sich auch Schwankungen im Frequenzbereich bei verschiedenen Sender-Empfängerkombinationen. Die Schallschwächung des Betons hat Einfluss auf die erreichbare Auflösung der Messungen und damit auf die maximal möglichen Senderabstände im Bauteil. Durch experimentelle Untersuchungen und Simulationen erfolgte eine Optimierung der Abstände hinsichtlich des Aufwandes und der geforderten Auflösung. Die Signalschwächung im Beton wurde mit verschiedenen Impulsen im Frequenzbereich von 50 kHz bis 100 kHz in Abhängigkeit verschiedener Bewehrungsgrade und Korngrößen ermittelt. Hierfür wurden die Sensoren in unterschiedlichen Abständen in die Probekörper einbetoniert und die Empfangssignale hinsichtlich Amplitudenabfall und Frequenzspektrum untersucht. T2 - DGZfP-Jahrestagung 2013 CY - Dresden, Germany DA - 06.05.2013 PY - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-294153 SN - 978-3-940283-49-8 IS - DGZfP-BB 141 (Poster 56) SP - 1 EP - 9 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung e.V. (DGZfP) AN - OPUS4-29415 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shokouhi, Parisa A1 - Wolf, Julia A1 - Wiggenhauser, Herbert T1 - Detection of delamination in concrete bridge decks by joint amplitude and phase analysis of ultrasonic array measurements N2 - The accuracy and precision of low-frequency (center frequency of approximately 55 kHz) ultrasonic testing for detection and characterization of delamination in concrete bridge decks were evaluated. A multiprobe ultrasonic testing system (with horizontally polarized shear-wave transducers) was used to detect built-in delamination defects of various size, depth, and severity (i.e., thickness) in a test specimen—a 6.1 m × 2.4 m × 216 mm (20 ft × 8 ft × 8.5 in.) reinforced concrete slab-built to simulate a concrete bridge deck. The collected data sets were reconstructed applying synthetic aperture focusing technique (SAFT). The reconstructed measurement results were then used to assess the condition of the concrete slab at individual points [point-by-point data collection and two-dimensional (2D) reconstruction] as well as along lines, where data were collected at smaller steps and reconstructed in a three-dimensional (3D) format. The local-phase information was also calculated, superimposed on the reconstructed images and used as complementary information in condition assessment. The precision and accuracy of condition assessments were evaluated. The results indicated that, using the multiprobe ultrasonic array, delamination defects as small as 30 cm² (1 ft²) could be reliably detected. Deep delaminations [i.e., those deeper than 150 mm (6 in.)] were directly detected and characterized, whereas shallow delaminations [shallower than 65 mm (2.5 in.)] were detected only indirectly. The precision of the measurements was demonstrated by comparing repeated measurements at several test points. Similar measurement results obtained on a delaminated portion of a real bridge deck support the conclusions of the validation study. KW - Concrete bridge deck KW - Bridge deck evaluation KW - Delamination KW - Nondestructive testing (NDT) KW - Ultrasonic testing PY - 2014 U6 - https://doi.org/10.1061/(ASCE)BE.1943-5592.0000513 SN - 1084-0702 VL - 19 IS - 3 SP - 04013005-1 - 04013005-11 PB - Soc. CY - Reston, Va. AN - OPUS4-31261 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - White, J. A1 - Wolf, Julia A1 - Shokouhi, Parisa A1 - Hurlebaus, S. A1 - Wimsatt, Andrew T1 - Concrete tunnel lining evaluation using nondestructive techniques: a multi-method case study at Eisenhower tunnel N2 - An in-depth investigation of tunnel linings is performed at Eisenhower Tunnel, 60 miles west of Denver, Colorado, using a combination of four nondestructive testing methods: air- and ground-coupled ground penetrating radar (GPR), ultrasonic echo (US echo), ultrasonic tomography (UST), and impact echo (IE). A robotic frame with pneumatically operated vacuum plates is used to automate GPR, US echo, and IE. UST was performed manually. These techniques are used to identify and locate the reinforcement mesh and structural steel ribs. Local changes in ultrasonic phase are calculated by phase analysis processing techniques and apparent relationships between positive and negative phase shifts and steel and air interfaces are observed. According to previous laboratory research, these relationships indicate the bonded state between the concrete and the embedded steel, but without ground truth verification this can only be suggested. It is shown that this combination of methods can be used synergistically to provide tunnel owners with the layout and possible condition of tunnel lining reinforcement and structural components. T2 - TRB 92nd Annual meeting CY - Washington, D.C., USA DA - 13.01.2013 KW - Nondestructive evaluation KW - Concrete KW - Ultrasonic KW - GPR KW - Impact echo PY - 2013 UR - http://trid.trb.org/view.aspx?id=1242002 SP - 1 EP - 16 AN - OPUS4-32025 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - White, J. A1 - Wolf, Julia A1 - Shokouhi, Parisa A1 - Hurlebaus, S. A1 - Wimsatt, Andrew T1 - Nondestructive evaluation of concrete linings at Hanging Lake tunnel N2 - Tunnel lining evaluation is performed in the Hanging Lake Tunnel near Glenwood Springs, Colorado, using variations of four nondestructive evaluation (NDE) methods: air- and ground-coupled ground penetrating radar (GPR), ultrasonic echo (US echo), ultrasonic tomography (UST), and impact echo (IE). Potential regions of interest are identified using high-speed air-coupled GPR and visual inspection. A robotic frame with pneumatically-operated vacuum plates was used to automate the ground-coupled GPR, US echo, and IE tests, while the UST technique was used manually. This study shows that a particular combination of NDE techniques is a powerful tool for assessing the condition of tunnel linings and can detect potential anomalies such as delamination, depth of surface cracks, reinforcement depth and layout, and lining thickness. By mapping the phase shift of the ultrasonic pulses at detected interface, the potential bonding of layer interfaces and reinforcement is assessed. T2 - TRB 92nd Annual meeting CY - Washington, D.C., USA DA - 13.01.2013 KW - Nondestructive evaluation KW - Concrete KW - Ultrasonic KW - GPR KW - Impact echo PY - 2013 UR - http://trid.trb.org/view.aspx?id=1241994 SP - 1 EP - 16 AN - OPUS4-32027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Milmann, Boris A1 - Helmerich, Rosemarie A1 - Köpp, Christian A1 - Wiggenhauser, Herbert A1 - Kurz, J.H. A1 - Moryson, R.M. A1 - Samokrutov, A. A1 - Alekhin, S. G. A1 - Alver, Ninel A1 - Sazak, H.Ö. T1 - An ultrasound monitoring system for concrete structures N2 - The research project "Ultrasonic Net for Concrete Monitoring (UNeCOM)" aims at developing a methodology for an embedded ultrasonic network for the condition assessment of infrastructure constructions. Civil engineering structures made of concrete, which are located in tectonically active regions or undergo special loading conditions, may require continuous monitoring. It is important to assess the condition of the building and its stability to recognise and classify the effect of a seismic event or evolving damage at early stages before failure occurs. Embedded ultrasonic sensors offer the possibility to detect changes in the material and degradation mechanisms from inside the structure in areas which are difficult or impossible to inspect otherwise. In contrast to conventional ultrasonic testing methods, where the concrete surfaces are scanned with ultrasound probes, this new approach uses sensors, which are embedded into concrete, eliminating the effect of variable coupling conditions between sensors and concrete. This method allows an integral detection of changes in the concrete structure, for example due to seismic activities, to detect mechanical impacts, as well as degradation of the material due to overloading. Such methods have great relevance especially for the monitoring of constructions like power plants, bridges, offshore structures and other structures with high technical safety requirements. The sensor network can be controlled remotely through the internet which is also being used for data transfer. The embedded sensor network is designed to monitor structural damage and concrete degradation globally with high sensitivity. T2 - Istanbul bridge conference 2014 CY - Istanbul, Turkey DA - 11.08.2014 KW - Ultrasound KW - Concrete KW - Monitoring PY - 2014 SN - 978-605-64131-6-2 SP - Paper 32, 1 EP - 9 AN - OPUS4-32028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, Julia A1 - Pirskawetz, Stephan A1 - Zang, A. T1 - Detection of crack propagation in concrete with embedded ultrasonic sensors N2 - This study evaluates the sensitivity of embedded ultrasonic sensors to detect propagating cracks within concrete. Because of the sensors constant coupling to the medium, highly sensitive data analysis techniques, such as the correlation between signals and their attenuation, are applied to detect changes in the signal due to propagating cracks. The accuracy of the detected onset of the crack is evaluated with the nondestructive testing methods acoustic emission and Digital Image Correlation. It shows that with embedded ultrasonic sensors crack propagation can be detected before it is visible on the surface of the concrete. KW - Embedded sensors KW - Ultrasound KW - Acoustic emission KW - Concrete KW - Cracks PY - 2015 U6 - https://doi.org/10.1016/j.engfracmech.2015.07.058 SN - 0013-7944 SN - 1873-7315 VL - 146 SP - 161 EP - 171 PB - Elsevier Science CY - Kidlington AN - OPUS4-34479 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pirskawetz, Stephan A1 - Wolf, Julia A1 - Schmidt, Wolfram A1 - Rogge, Andreas T1 - Einsatzmöglichkeiten der Schallemissionsanalyse im Bauwesen N2 - Die Schallemissionsanalyse (SEA) ist ein passives zerstörungsfreies Prüfverfahren. mit dem Rissbildung, Risswachstum und andere Gefügeveränderungen delektiert und lokalisiert werden können. Anhand von zwei Beispielen aus der Forschung der Bundesanstalt für Materialforschung und -prüfung (BAM) wird gezeigt welche Möglichkeiten die SEA beim Bauwerksmonitoring und bei der Untersuchung von Baustoffen bietet. Im ersten Beispiel wird die Ortung von Schallemissionen zur Verfolgung des Risswachstums in Beton eingesetzt. Weiterhin wird mit Zugversuchen an Faserbeton illustriert, dass mit der SEA Versagensmechanismen identifiziert werden können. T2 - 8. Symposium Experimentelle Untersuchungen von Baukonstruktionen CY - Dresden, Germany DA - 24.09.2015 KW - Schallemission KW - SHCC PY - 2015 SN - 1613-6934 N1 - Serientitel: Schriftenreihe Konstruktiver Ingenieurbau Dresden – Series title: Schriftenreihe Konstruktiver Ingenieurbau Dresden VL - 40 SP - 61 EP - 72 PB - Technische Universität Dresden CY - Dresden AN - OPUS4-34581 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Milmann, Boris A1 - Wiggenhauser, Herbert T1 - Grundlagenuntersuchungen von Ultraschall-Sensoren in Beton T2 - DGZfP Jahrestagung CY - Dresden DA - 2013-05-06 PY - 2013 AN - OPUS4-32993 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Wiggenhauser, Herbert T1 - Eingebettete Ultraschall-Sensoren zur Dauerüberwachung von Betonbauteilen T2 - 74. Jahrestagung der Deutschen Geophysikalischen Gesellschaft (DGG) CY - Karlsruhe, Deutschland DA - 2014-03-10 PY - 2014 AN - OPUS4-32600 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Wiggenhauser, Herbert T1 - Using embedded ultrasonic sensors for active and passive concrete monitoring N2 - Challenging new constructions and ageing infrastructure are increasing the demand for permanent monitoring of loads and condition. Various methods and sensors are used for this purpose. But the technologies available today have difficulties in detecting slowly progressing locally confined damages. Extensive investigations or instrumentations are required so far for this purpose. In this study we present new sensors and data processing methods for ultrasonic transmission, which can be used for non-destructive long term monitoring of concrete. They can be mounted during construction or thereafter. Larger volumes can be monitored by a limited number of sensors for changes of material properties. The principles of ultrasonic transmission and influencing factors are presented. This latter include load, damages as well as environmental parameters as temperature or moisture. Various methods for data processing, e. g. coda wave interferometry are introduced. They allow the detection of very small changes in the medium. The embedded sensors are shown including mounting and operation. Application examples so far include small scale laboratory freeze-thaw experiments, localizing loads in larger concrete models, monitoring load effects on real structures as well as detecting acoustic events. Some sensors are operating already for several years. The sensors can be used as transmitter or receivers or switched between both roles. While most of the previous experiments have been active (at least one sensor serving as transmitter), new studies show that the sensors are useful as well for passive measurements, e. g. in acoustic emission or time reversal experiments. Besides application in civil engineering our setups can also be used for model studies in geosciences. T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering CY - Berlin, Germany DA - 15.09.2015 KW - SHM KW - Monitoring KW - Ultrasound concrete KW - Embedded sensors PY - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-344652 UR - http://www.ndt.net/?id=18408 SN - 1435-4934 VL - 20 IS - 11 SP - 1 EP - 4 PB - NDT.net CY - Kirchwald AN - OPUS4-34465 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, Julia A1 - Niederleithinger, Ernst A1 - Mielentz, Frank A1 - Grothe, Sven A1 - Wiggenhauser, Herbert T1 - Überwachung von Betonkonstruktionen mit eingebetteten Ultraschallsensoren N2 - Die immer komplexere Konstruktionsweise von Neubauten einerseits und die alternde Infrastruktur andererseits erfordern in manchen Fällen eine dauerhafte Überwachung, um besondere Einwirkungen und gegebenenfalls Schädigungen rechtzeitig und genau zu erkennen. Hierfür ist eine Vielzahl von Methoden und Sensoren verfügbar. Das Portfolio weist aber insbesondere bei der Detektion langsamer, räumlich begrenzter Veränderungen Lücken auf. Hierfür sind bisher sehr aufwändige Untersuchungen oder Installationen notwendig. In der vorliegenden Arbeit werden Sensoren und zugehörige Auswertemethoden für die Ultraschalltransmission vorgestellt, die sich für die zerstörungsfreie, dauerhafte Überwachung von Beton eignen. Direkt oder nachträglich in Betonkonstruktionen eingebaut, ermöglichen sie eine nicht nur lokale, sondern größere Raumbereiche umfassende Dauerüberwachung von Änderungen der Materialeigenschaften. Das Prinzip der Ultraschalltransmission und die verschiedenen Einflussparameter werden vorgestellt. Zu letzteren gehören neben der Belastung und Schädigung auch Umweltparameter wie Temperatur und Feuchte. Verschiedene Methoden zur Datenanalyse, wie z. B. die Codawelleninterferometrie, ermöglichen eine Detektion kleinster Veränderungen. Die in den Beton einzubettenden Ultraschallsensoren werden vorgestellt und ihr Einbau und Betrieb beschrieben. Als Beispiele für Anwendungen werden Frost-Tauwechsel-Experimente im Labor, die Detektion von lokalen Lasten im Technikumsmaßstab und der Einsatz an realen Brücken diskutiert. Die Sensoren sind zum Teil bereits seit mehreren Jahren in Probeobjekte eingebettet und liefern zuverlässig wertvolle Daten.------------------------------------------------------------------------------------------------------------------------------------------------------------- Monitoring of concrete constructions by embedded ultrasonic sensors: Challenging new constructions and the ageing infrastructure are increasing the demand for permanent monitoring of loads and damages. Various methods and sensors are used for this purpose. But the technologies available today have difficulties in detecting slowly progressing locally confined damages. Extensive investigations or instrumentations are required so far for this purpose. In this study we present new sensors and data processing methods for ultrasonic transmission, which can be used for non-destructive permanent monitoring of concrete. They can be mounted during construction or thereafter. Larger volumes can be monitored by a limited number of sensors for changes of material properties. The principles of ultrasonic transmission and influencing factors are presented. This latter include load, damages as well as environmental parameters as temperature or moisture. Various methods for data processing, e. g. coda wave interferometry are introduced. They allow the detection of very small changes in the medium. The embedded sensors are shown including mounting and operation. Application examples so far include small scale laboratory freeze-thaw experiments, localizing loads in larger concrete models and monitoring load effects on real structures. Some sensors are operating already for several years. KW - Beton KW - Ultraschall KW - Transmission KW - Monitoring KW - Codawelleninterferometrie KW - Frost-Tauwechsel KW - Ultraschallsensoren, eingebettete KW - Lastconcrete KW - Ultrasound KW - Coda wave interferometry KW - Embedded sensors KW - Freeze-thaw KW - Load KW - Neue Verfahren/Versuchstechnik KW - New Processes/Experimental Techniques PY - 2014 U6 - https://doi.org/10.1002/bate.201400073 SN - 0932-8351 SN - 1437-0999 SN - 0005-6820 SN - 0341-1052 SN - 0932-6359 VL - 91 IS - 11 SP - 783 EP - 796 PB - Ernst & Sohn CY - Berlin AN - OPUS4-32077 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Wiggenhauser, Herbert A1 - Pirskawetz, Stephan T1 - Embedded ultrasonic transducers for active and passive concrete monitoring N2 - Recently developed new transducers for ultrasonic transmission, which can be embedded right into concrete, are now used for non-destructive permanent monitoring of concrete. They can be installed during construction or thereafter. Large volumes of concrete can be monitored for changes of material properties by a limited number of transducers. The transducer design, the main properties as well as installation procedures are presented. It is shown that compressional waves with a central frequency of 62 kHz are mainly generated around the transducer's axis. The transducer can be used as a transmitter or receiver. Application examples demonstrate that the transducers can be used to monitor concrete conditions parameters (stress, temperature, …) as well as damages in an early state or the detection of acoustic events (e.g., crack opening). Besides application in civil engineering our setups can also be used for model studies in geosciences. KW - Ultrasound KW - Transmission KW - Concrete KW - Damages KW - Cracks KW - Stress KW - Monitoring KW - Acoustic emission KW - Transducers KW - Coda wave interferometry PY - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-345632 SN - 1424-8220 VL - 15 IS - 5 SP - 9756 EP - 9772 PB - MDPI CY - Basel AN - OPUS4-34563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -