TY - GEN A1 - Bernhardt, Yannick A1 - Császár, Lukas A1 - Dengiz, Nizamettin A1 - Fuchs, Martin A1 - Gaal, Mate A1 - Gautzsch, Tobias A1 - Gohlke, Dirk A1 - Hahn-Jose, Thomas A1 - Heckel, Thomas A1 - Hillger, Wolfgang A1 - Hufschläger, Daniel A1 - Ilse, Detlef A1 - Kiel, Mario A1 - Kornely, Mike A1 - Labud, Patrick Alexander A1 - Marhenke, Torben A1 - Schubert, Frank A1 - Sommerhuber, Ryan A1 - Steinhausen, Ralf A1 - Szewieczek, Artur A1 - Wachter, Luis A1 - Waschkies, Thomas T1 - Charakterisierung und Verifizierung der luftgekoppelten Ultraschallprüfköpfe N2 - Dieses Dokument beschreibt die Eigenschaft en von fokussierten und unfokussierten Prüfköpfen, die für die zerstörungsfreie luftgekoppelte Ultraschallprüfung mit Mittenfrequenzen von über 20 kHz verwendet werden. Dieses Dokument bezieht sich auf Prüfköpfe, die auf dem piezoelektrischen Effekt basieren. KW - Luftgekoppelter Ultraschall KW - Ultraschallprüfung KW - Prüfköpfe KW - Charakterisierung PY - 2024 SN - 978-3-947971-36-7 VL - Richtlinie US 08 SP - 1 EP - 24 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin ET - Ausgabe Mai 2024 AN - OPUS4-62489 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kind, Thomas A1 - Trela, Christiane A1 - Schubert, Marcus A1 - Wöstmann, Jens ED - Lambot, S. ED - Giannopoulos, A. ED - Pajewski, L. ED - André, F. ED - Slob, E. ED - Craeye, C. T1 - Aggregates scattering of GPR waves in concrete N2 - Time slices of very dense GPR measurements carried out at concrete with a real point distance of less than 10 mm in x and y direction show weak reflection patterns besides the strong reflections of reinforcements. A repetition of these measurements with the same local geometrical precision at the same specimen shows the same reflection pattem. We suppose that the heterogeneity of concrete given by aggregates (e.g. gravel, broken granite) causes local weak Scattering of the GPR waves and leads to reflection patterns in the GPR data. These reflection patterns can be explained by a Superposition of multiple scatterings of single aggregates. So far these reflection patterns have been not recognized in Standard time slices due to the large spacing (> 5 cm) between single profiles and because of the interpolation between the profiles. We investigate the characteristics of the volume scattering effects, caused by aggregates, at concrete blocks with two different grading curves. In a more general investigation we study the volume scattering of aggregates by using wooden boxes filled with only typical aggregates and an included defined reflector (metal plate). The thickness of the aggregate layer above the metal plate was varied between 20 cm and 40 cm. With a very dense measuring grid at the surface we are able to calculate the effective volume scattering and to analyze the distribution of the reflection amplitude of the included metal plate for different aggregate set-ups. Results of this study confirm that the weak reflection patterns in concrete can be explained by aggregate scattering and have a direct correlation to the penetration depth of GPR in concrete. T2 - GPR 2014 - 15th International conference on ground penetrating radar CY - Brussels, Belgium DA - 30.06.2014 KW - Aggregates KW - Volume scattering PY - 2014 UR - http://sites.uclouvain.be/GPR2014 SP - 933 EP - 938 AN - OPUS4-34576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Bernhardt, Y. A1 - Csaszar, L. A1 - Dengiz, N. A1 - Fuchs, M. A1 - Gautzsch, T. A1 - Gohlke, Dirk A1 - Hahn-Jose, T. A1 - Heckel, Thomas A1 - Hillger, W. A1 - Hufschläger, Daniel A1 - Ilse, D. A1 - Kiel, M. A1 - Labud, P. A1 - Schubert, F. A1 - Sommerhuber, R. A1 - Szewieczek, A. A1 - Waschkies, T. T1 - Richtlinie zur Charakterisierung von luftgekoppelten Ultraschallwandlern N2 - Zur Charakterisierung von luftgekoppelten Ultraschallwandlern werden mehrere verschiedene Methoden und Verfahren angewendet. Durch die unterschiedlichen Herangehensweisen werden oft unterschiedliche Prüfkopfpara-meter und Schallfeldgrößen ermittelt, was einen direkten Vergleich von Datenblättern erschwert. Für die Charakterisierung von Kontakt- und Tauchtechnikprüfköpfen hat sich ISO 22232-2:2021 bereits etabliert, allerdings ist diese Norm nicht auf die luftgekoppelten Wandlertechnologien direkt übertragbar. Daher erkannten Hersteller, Forschungseinrichtungen und Anwender den Bedarf an einer Richtlinie zur einheitlichen Charakterisierung von luftgekoppelten Wandlern. Gemeinsam arbeiten sie aktuell im Rahmen des Unterausschusses „Luftgekoppelte Ultraschallprüfung“ der DGZfP an der Erstellung einer solcher Richtlinie mit dem Anspruch, die bestehende Normung um die luftgekoppelte Prüfung zu erweitern und somit die Vereinheitlichung der Charakterisierung dieser Wandler zu erleichtern. In diesem Beitrag wird ein Überblick über den geplanten Inhalt der Richtlinie und über die Methoden zur akustischen Charakterisierung von luftgekoppelten Ultraschallwandlern gegeben. Insbesondere werden verschiedene Methoden der Ermittlung von wichtigen Wandlerparametern wie z.B. Empfindlichkeit, Mittenfrequenz, Bandbreite, Fokusgröße und Fokusabstand dargestellt und verglichen. T2 - DGZfP-Jahrestagung CY - Kassel, Germany DA - 23.05.2022 KW - Lutgekoppelte Ultraschallprüfung KW - Prüfkopf KW - Charakterisierung KW - Richtlinie PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-552918 SP - 1 EP - 7 AN - OPUS4-55291 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bernhardt, Y. A1 - Császár, L. A1 - Dengiz, N. A1 - Fuchs, M. A1 - Gaal, Mate A1 - Gautzsch, T. A1 - Gohlke, Dirk A1 - Hahn-Jose, T. A1 - Heckel, Thomas A1 - Hillger, W. A1 - Hufschläger, Daniel A1 - Ilse, D. A1 - Kiel, M. A1 - Kornely, M. A1 - Labud, P. A. A1 - Marhenke, T. A1 - Schubert, F. A1 - Sommerhuber, R. A1 - Steinhausen, R. A1 - Szewieczek, A. A1 - Wachter, L. A1 - Waschkies, T. T1 - Characterization and verification of air-coupled ultrasonic probes N2 - This guideline was drafted following and complementing the norm ISO 22232-2:2020(E) to include air-coupled ultrasonic transducers. This document specifies the characteristics of probes used for non-destructive air-coupled ultrasonic testing with center frequencies above 20 kHz, with focusing or without focusing means. KW - Air-coupled ultrasound KW - Ultrasonic testing KW - Guideline KW - Probe KW - Characterization PY - 2022 SN - 978-3-947971-26-8 VL - Guideline US 08 SP - 1 EP - 23 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) CY - Berlin ET - Edition September 2022 AN - OPUS4-56228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trela, Christiane A1 - Kind, Thomas A1 - Schubert, Marcus A1 - Klee, Martin ED - Lambot, S. ED - Giannopoulos, A. ED - Pajewski, L. ED - André, F. ED - Slob, E. ED - Craeye, C. T1 - Detection of weak scatterers in reinforced concrete structures N2 - GPR surveys on concrete structures like bridges, dccks and buildings are succcssfully applied to detect and localize construction elements mostly madc of metal. Dcfects like air voids behind rebars in incompletely compacted concrete still represent major challenges due to thcir weak reflcction amplitudes. In a systcmatic study at a concrete test specimen with vcrtical rebars and simulated air voids of different size and depth, the effects of different GPR data acquisition Parameters like antenna frcqucncies (1.2 up to 2.6 GHz) and antenna orientation on the quality of imaging of thcsc air voids wcre investigated. Vcry dense measurements with high Position accuracy were carried out using an automated scanning System. Despite the strong shadowing and disturbing interference effccts of the reinforccmcnt and the associated strong rcflections, the weak scatterers can still be identified to a ccrtain depth using appropriate antenna configurations. Measurements with the antenna orientation perpendicular to the rebars of 1.2 to 2.0 GHz give the best results. Pre- and postprocessing steps like filtering, gain, 3D SAFT (Synthetic Apcrture Focusing Technique) rcconstruction and somc adapted visualization options were properly applied to improve the imaging results of thcsc weak scatterers. T2 - GPR 2014 - 15th International conference on ground penetrating radar CY - Brussels, Belgium DA - 30.06.2014 KW - Radarmessungen KW - Automatisierung KW - Strukturerkennung KW - Stahlbeton KW - Reflection profiling KW - Data processing KW - SAFT reconstruction and visualisation of NDT-datasets PY - 2014 N1 - Geburtsname von Klee, Martin: Günther, M. - Birth name of Klee, Martin: Günther, M. SP - 904 EP - 910 AN - OPUS4-31168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trela, Christiane A1 - Kind, Thomas A1 - Schubert, Marcus T1 - Detection of air voids in concrete by radar in transmission mode N2 - Air voids in concrete like honeycombs are one of the major concerns regarding quality assurance for the construction of infrastructure buildings like bridges or tunnels. This paper shows that voids in reinforced concrete walls or slabs can be detected by two standard ground coupled GPR antennas in transmission mode using a two-side zero-offset profiling configuration like in borehole radar applications. For the detection of voids only the amplitudes of the direct wave in transmission mode are evaluated. Even when the depth of the void can not be detected in this configuration, the major advantage of the zero-offset profiling in transmission mode is a lower interference with the surrounding reinforcement compared to a regular one-side reflection profiling. The capability of the two-side zero-offset profiling is demonstrated on a test specimen with a set of polystyrene balls of two different sizes representing voids like honeycombs in concrete. GPR measurements are realized by an automated scanning system in order to allow for a synchronous movement of the antennas. In transmission mode voids can be detected at greater depths compared to reflection mode, since the travel path of the direct wave is half as long. Another characteristic of the transmission mode is that the direct wave through the air voids is faster and arrives earlier than the direct wave in the surrounding concrete. Hence it can be separated from the strong reflection of the reinforcement. Finally the measurements in transmission mode are less sensitive to the antenna frequency and polarization than in reflection mode. T2 - IWAGPR 2015 - 8th International workshop on advanced ground penetrating radar CY - Firenze, Italy DA - 07.07.2015 KW - Radar KW - Zerstörungsfreie Prüfung KW - Ground penetrating radar KW - Transmission KW - Reinforced concrete KW - Honeycombs KW - Void detection KW - First arrival PY - 2015 SN - 978-1-4799-6495-6 DO - https://doi.org/10.1109/IWAGPR.2015.7292650 AN - OPUS4-34678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Quercetti, Thomas A1 - Müller, Karsten A1 - Schubert, Sven T1 - Comparison of experimental results from drop testing of a spent fuel package design using a full-scale prototype model and a reduced-scale model T2 - PATRAM 2007, 15th International Symposium on the Packaging and Transportation of Radioactive Materials CY - Miami, Florida, USA DA - 2007-10-21 KW - Drop KW - Testing KW - Experiment KW - Prototype KW - Reduced-scale KW - Full-scale PY - 2007 SP - 1 EP - 8 PB - Institute of Nuclear Materials Management AN - OPUS4-18624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quercetti, Thomas A1 - Müller, Karsten A1 - Schubert, Sven T1 - Comparison of experimental results from drop testing of spent fuel package design using full scale prototype model and reduced scale model N2 - This paper presents a comparison between full scale prototype and reduced scale model drop test data in regard to similarity mechanics. Together with a current BAM research project, the paper contributes to the further development of mechanical evaluation methods for safety assessment of RAM transport and storage packages including the transferability of package impact response from reduced scale models to full scale packages. KW - Full scale KW - Reduced scale KW - Drop testing KW - Similarity PY - 2008 DO - https://doi.org/10.1179/174651008X362575 SN - 1746-5095 SN - 1746-5109 SN - 0957-476X VL - 19 IS - 4 SP - 197 EP - 202 PB - Ramtrans Publ. CY - Ashford AN - OPUS4-20135 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Goedecke, Thomas A1 - Schubert, Sven T1 - Rolling home PY - 2002 SN - 0016-5808 VL - 45 IS - 5 SP - 27 EP - 29 PB - Storck CY - Hamburg AN - OPUS4-1881 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabitz, Konstantin Manuel A1 - Antretter, Thomas A1 - Rethmeier, Michael A1 - El-Sari, Bassel A1 - Schubert, Holger A1 - Hilpert, Benjamin A1 - Gruber, Martin A1 - Sierlinger, Robert A1 - Ecker, Werner T1 - Numerical and experimental assessment of liquid metal embrittlement in externally loaded spot welds N2 - Zinc-based surface coatings are widely applied with high-strength steels in automotive industry. Some of these base materials show an increased brittle cracking risk during loading. It is necessary to examine electrogalvanized and uncoated samples of a high strength steel susceptible to liquid metal embrittlement during spot welding with applied external load. Therefore, a newly developed tensile test method with a simultaneously applied spot weld is conducted. A fully coupled 3D electrical, thermal, metallurgical and mechanical finite element model depicting the resistant spot welding process combined with the tensile test conducted is mandatory to correct geometric influences of the sample geometry and provides insights into the sample’s time dependent local loading. With increasing external loads, the morphology of the brittle cracks formed is affected more than the crack depth. The validated finite element model applies newly developed damage indicators to predict and explain the liquid metal embrittlement cracking onset and development as well as even ductile failure. KW - Resistance spot welding KW - Finite element simulation KW - Advanced high-strength steel KW - Liquid metal embrittlement KW - Damage prediction KW - Tensile resistance spot welding experiment PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594848 DO - https://doi.org/10.1007/s40194-024-01696-7 SN - 0043-2288 SP - 1 EP - 10 PB - Springer Science and Business Media LLC AN - OPUS4-59484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Trela, Christiane A1 - Kind, Thomas A1 - Schubert, Marcus T1 - Positioning accuracy of an automatic scanning system for GPR measurements on concrete structures N2 - Most GPR measurements use hand-held survey wheels for positioning, something not feasible in some scenarios, such as measuring a tall retaining wall, tunnels or if tedious and repetitive measurements are required. For situations like these an automated positioning system is required and was therefore developed at BAM. Such a system was tested to calibrate the positioning of a GPR grid measurement which was performed in regular one-direction traverse mode and in a meandric mode. The preliminary results show a systematic error in the positioning, which depends on the traveling speed of the scanning system, because there is an electronic delay of the trigger signal. These errors are duplicated in meandric mode compared to the errors occurring in one-direction traverse mode. This may be insignificant when larger objects are investigated, but can be important for the identification and location of small objects which show weaker reflections, like e.g. compacting faults with a size of a honeycomb. T2 - 14th International conference on ground penetrating radar - GPR 2012 CY - Shanghai, China DA - 04.06.2012 KW - Automated scanning systems KW - Accuracy of positioning KW - Ground penetration radar PY - 2012 SN - 978-1-4673-2663-6 VL - I SP - 309 EP - 313 AN - OPUS4-26074 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schubert, Thomas A1 - Máca, Petr A1 - Hering, Marcus A1 - Fiedler, Georg A1 - Beckmann, Birgit T1 - Impact Experiments on Reinforced Concrete Specimens - Investigation of Repeatability and Scaling N2 - Nowadays, the impact resistance of concrete structures has become a prominent concern for critical infrastructure operators, particularly amidst escalating geopolitical tensions. Regulators and design engineers know that reinforced concrete structures can only be developed with high efficiency by considering nonlinear structural and highly nonlinear material behavior. Therefore, specific guidelines on impact design provide instructions for design and analysis of structures required to resist impact loading. These instructions are usually based on published results and evaluated data of impact experiments carried out in laboratories. To widen the knowledge and increase the scientific data the Institute of Concrete Structures (IMB) at TUD Dresden University of Technology (TUD) has carried out many impact experiments on reinforced concrete specimens in recent years. A specially designed drop tower is available for this purpose on the premises of the Otto Mohr Laboratory, TUD. In the framework of the past research at TUD some important issues, such as influence of rebar arrangement, structural thickness, scalability of specimen and repeatability, with regard to experimental impact testing were investigated. This article presents the drop tower facility and research results of impact experiments on reinforced concrete slabs. First, the scalability of impact experiments will be discussed in conjunction with already known theoretical scaling parameters provided by researchers in the past, e.g. Rüdiger et al. [1]. Scalability of experimental data is of huge importance since protective structures made of reinforced concrete differ usually in size in comparison to experimental specimens. The second important research focus is on repeatably of impact experiments. Since impact experiments are usually time consuming and expensive, a certain impact scenario is mostly carried out only once. It is intended to show the range of deviation of impact tests on some already carried out experiments on reinforced concrete slabs. A possible standard deviation is estimated for the applied test setup. T2 - 15th International Conference on Shock & Impact Loads on Structures CY - Gothenburg, Sweden DA - 12.06.2025 KW - Reinforced concrete KW - Drop-weight impact KW - Scaling KW - Repeatability KW - Digital image correlation PY - 2025 SP - 80 EP - 91 AN - OPUS4-63627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -