TY - JOUR A1 - Mielentz, Frank T1 - Phased Arrays for Ultrasonic Investigations in Concrete Components JF - Journal of nondestructive evaluation N2 - An innovative application of ultrasonic testing using phased arrays for concrete components was investigated. A low frequency ultrasonic phased array consisting of ten transducers was used. This configuration allowed the variation and control of the sound field directivity during the measurement. The measurements were carried out on concrete test specimens using a scanning laservibrometer in through transmission mode. The laboratory measurements were compared to theoretical calculations to investigate the influence of shape and dimension of the transducer on the resulting sound field patterns. The technique was successfully implemented to detect an ungrouted tendon duct in a concrete block. KW - Ultrasonic-echo KW - Concrete KW - Array technique KW - Phased array KW - Point source synthesis PY - 2008 DO - https://doi.org/10.1007/s10921-008-0032-6 SN - 0195-9298 SN - 1573-4862 VL - 27 IS - 1-3 SP - 23 EP - 33 PB - Plenum Press CY - New York, NY AN - OPUS4-17929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Krause, Martin A1 - Mielentz, Frank A1 - Milmann, Boris A1 - Streicher, Doreen A1 - Mayer, K. T1 - Ultrasonic Reflection Properties at Interfaces Between Concrete Steel and Air: Imaging and Modelling T2 - NDE Conference on Civil Engineering T2 - NDE Conference on Civil Engineering CY - St. Louis, Missouri, USA DA - 2006-08-14 KW - Ultrasonic echo KW - Concrete PY - 2006 SN - 1-57117-148-7 SP - 472 EP - 479 PB - ASTM CY - St. Louis AN - OPUS4-14239 LA - eng 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 T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure (Proceedings) 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 - 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 T2 - Istanbul bridge conference 2014 (Proceedings) 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 - Mielentz, Frank A1 - Feller, Viktor A1 - Krause, Martin A1 - Orglmeister, R. T1 - Ultraschallprüfung von Betonbauteilen - laufzeitgesteuerte Gruppenstrahler mit Punktkontaktprüfköpfen JF - Materials Testing N2 - In den letzten Jahren werden vermehrt trocken ankoppelbare Ultraschall-Punktkontaktprüfköpfe erfolgreich für Prüfaufgaben im Bauwesen angewendet. Oft werden mehrere Punktkontaktprüfköpfe in einem Gehäuse zu einer Strahlergruppe kombiniert, um die Schallbündelung zu verbessern oder um einzelne Prüfköpfe nacheinander als Sender und Empfänger zu betreiben und die Messsignale nach der Messung einer SAFT-Auswertung zuzuführen. Alternativ können die einzelnen Prüfköpfe einer solchen Gruppe laufzeitgesteuert angeregt und dadurch schon während der Messung das Prüfkopfschallfeld beeinflusst werden. Für diese Technik sind die Bezeichnungen laufzeitgesteuerte Ultraschall-Gruppenstrahler oder 'Phased Array' gebräuchlich. Mit den präsentierten Untersuchungen sollen die Anwendungsmöglichkeiten der Gruppenstrahlertechnik im Niederfrequenzbereich durch den Einsatz von Punktkontaktprüfköpfen verbessert werden. Dazu werden verschiedene Wellenarten eingesetzt und der Einfluss der Anordnung der Strahlerelemente im Array untersucht. KW - Ultra sonic testing KW - Concrete KW - Phased array KW - Point contact probes KW - Beton KW - Ultraschallprüfung KW - Laufzeitgesteuerte Gruppenstrahler KW - Punktkontaktprüfköpfe PY - 2015 UR - http://www.hanser-elibrary.com/doi/pdf/10.3139/120.110723 SN - 0025-5300 VL - 57 IS - 4 SP - 329 EP - 336 PB - Hanser CY - München AN - OPUS4-33064 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Feller, Viktor A1 - Mielentz, Frank A1 - Klewe, T. A1 - Krause, Martin A1 - Orglmeister, R. A1 - Pflugradt, M. T1 - Ultrasonic phased array for investigations of concrete components T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering (Proceedings) N2 - This paper describes an innovation of a phased array using dry contact probes to test concrete components. Based on preceding work on pressure waves, a low-frequency ultrasonic phased array consisting of shear wave probes is used in the experiments. This configuration allows the variation and control of the sound field directivity during the measurement. The measurements are carried out on a concrete test block using a scanning laservibrometer and a scanner system in transmission mode. The laboratory measurements are compared to theoretical calculations to investigate the influence of the probes shape and dimension on the resulting sound field patterns. The comparison of the modelling and the measurements demonstrates the suitability of the point source synthesis as a tool for the optimization of probe array designs. Methods of coded are used to improve the signal to noise ratio. T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering CY - Berlin, Germany DA - 15.09.2015 KW - Ultrasonic KW - Phased array KW - Concrete KW - Point source synthesis PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-350417 UR - http://www.ndt.net/article/ndtce2015/papers/059_feller_viktor.pdf SN - 1435-4934 SP - 1 EP - 5 PB - Technische Universität Berlin / Bundesanstalt für Materialforschung und -prüfung AN - OPUS4-35041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Gardner, S. A1 - Kind, Thomas A1 - Kaiser, R. A1 - Grunwald, Marcel A1 - Yang, G. A1 - Redmer, Bernhard A1 - Waske, Anja A1 - Mielentz, Frank A1 - Effner, Ute A1 - Köpp, Christian A1 - Clarkson, A. A1 - Thompson, F. A1 - Ryan, M. A1 - Mahon, D. T1 - Muon Tomography of the Interior of a Reinforced Concrete Block: First Experimental Proof of Concept JF - Journal of Nondestructive Evaluation N2 - Quality assurance and condition assessment of concrete structures is an important topic world-wide due to the aging infrastructure and increasing traffic demands. Common topics include, but are not limited to, localisation of rebar or tendon ducts, geometrical irregularities, cracks, voids, honeycombing or other flaws. Non-destructive techniques such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features. Until the 1980s X-ray transmission was used in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened up new fields of application, such as the investigation of freight containers. Muon imaging also has the potential to fill some of the gaps currently existing in concrete NDT. As a first step towards practical use and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. The data acquisition takes more time and signals contain more noise, but the images allowed to detect the same important features that are visible in conventional high energy X-ray tomography. In our experiment, we have shown that muon imaging has potential for concrete inspection. The next steps include the development of mobile detectors and optimising acquisition and imaging parameters. KW - Concrete KW - Muon KW - Radar KW - Ultrasound KW - X-ray PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-529974 DO - https://doi.org/10.1007/s10921-021-00797-3 VL - 40 IS - 3 SP - 1 EP - 14 PB - Springer Nature AN - OPUS4-52997 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabhakara, Prathik A1 - Mielentz, Frank A1 - Stolpe, Heiko A1 - Behrens, Matthias A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Validation of novel ultrasonic phased array borehole probe by using simulation and measurement JF - Sensors N2 - Low-frequency ultrasonic testing is a well-established non-destructive testing (NDT) method in civil engineering for material characterization and the localization of cracks, reinforcing bars and delamination. A novel ultrasonic borehole probe is developed for in situ quality assurance of sealing structures in radioactive waste repositories using existing research boreholes. The aim is to examine the sealing structures made of salt concrete for any possible cracks and delamination and to localize built-in components. A prototype has been developed using 12 individual horizontal dry point contact (DPC) shear wave transducers separated by equidistant transmitter/receiver arrays. The probe is equipped with a commercially available portable ultrasonic flaw detector used in the NDT civil engineering industry. To increase the sound pressure generated, the number of transducers in the novel probe is increased to 32 transducers. In addition, the timed excitation of each transducer directs a focused beam of sound to a specific angle and distance based on the previously calculated delay time. This narrows the sensitivity of test volume and improves the signal-to-noise ratio of the received signals. In this paper, the newly designed phased array borehole probe is validated by beam computation in the CIVA software and experimental investigations on a half-cylindrical test specimen to investigate the directional characteristics. In combination with geophysical reconstruction methods, it is expected that an optimised radiation pattern of the probe will improve the signal quality and thus increase the reliability of the imaging results. This is an important consideration for the construction of safe sealing structures for the safe disposal of radioactive or toxic waste. KW - Ultrasound KW - Phased array KW - Concrete KW - Borehole PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-565722 DO - https://doi.org/10.3390/s22249823 SN - 1424-8220 VL - 22 IS - 24 SP - 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-56572 LA - eng 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 JF - Sensors 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 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-345632 DO - https://doi.org/10.3390/s150509756 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 -