TY - CONF A1 - Ratkovac, Mirjana A1 - Gerards-Wünsche, Paul A1 - Thiele, Marc A1 - Brackrock, Daniel A1 - Stamm, Michael T1 - Detection and monitoring of the fatigue crack growth on welds – Application-oriented use of NDT methods N2 - Early detection of fatigue cracks and accurate measurements of the crack growth play an important role in the maintenance and repair strategies of steel structures exposed to cyclic loads during their service life. Observation of welded connections is especially of high relevance due to their higher susceptibility to fatigue damage. The aim of this contribution was to monitor fatigue crack growth in thick welded specimens during fatigue tests as holistically as possible, by implementing multiple NDT methods simultaneously in order to record the crack initiation and propagation until the final fracture. In addition to well-known methods such as strain gauges, thermography, and ultrasound, the crack luminescence method developed at the Bundesanstalt für Materialforschung und -prüfung (BAM), which makes cracks on the surface particularly visible, was also used. For data acquisition, a first data fusion concept was developed and applied in order to synchronize the data of the different methods and to evaluate them to a large extent automatically. The resulting database can ultimately also be used to access, view, and analyze the experimental data for various NDT methods. During the conducted fatigue tests, the simultaneous measurements of the same cracking process enabled a comprehensive comparison of the methods, highlighting their individual strengths and limitations. More importantly, they showed how a synergetic combination of different NDT methods can be beneficial for implementation in large-scale fatigue testing but also in monitoring and inspection programs of in-service structures - such as the support structures of offshore wind turbines. T2 - Fatigue Design 2023 (FatDes 2023) CY - Senlis, France DA - 29.11.2023 KW - Fatigue KW - Welded KW - NDT KW - Crack growth PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600238 DO - https://doi.org/10.1016/j.prostr.2024.03.062 VL - 57 SP - 560 EP - 568 PB - Elsevier B.V. AN - OPUS4-60023 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thibaux, Philippe A1 - Thiele, Marc A1 - Van Wittenberghe, Jeroen A1 - Baeßler, Matthias T1 - Comparison of resonance and hydraulic testing on large scale fatigue tests of welded tubular joints for offshore wind turbine foundations N2 - Jackets structures as foundations for offshore wind energy converters are efficient solutions. But these structures require the welding of a large number of joints. The design of the Jacket structures is typically driven by fatigue. Therefore, consequently the fatigue strength of the joints is a primary parameter for an optimized design. The present paper investigates if tubular joints produced by manual welding using the current techniques have an improved performance compared to the relevant standards that are applied for the design of the foundations. To investigate this, 4 full-scale tests in geometry representative of a structure were performed, 2 using a resonance method and 2 using a three-point bending method with hydraulic actuators. The results are similar, with cracks initiated early and extending extensively before failure. The results are very close to the current T-curve from DNV RP-C203 applied for tubular joints. KW - Fatigue KW - Tubular joints KW - Resonance testing KW - Steel welds PY - 2025 DO - https://doi.org/10.1016/j.ijfatigue.2024.108797 SN - 0142-1123 VL - 193 SP - 1 EP - 16 PB - Elsevier Ltd. AN - OPUS4-62373 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiele, Marc A1 - Pirskawetz, Stephan T1 - Analysis of damage evolution in concrete under fatigue loading by acoustic emission and ultrasonic testing N2 - The fatigue process of concrete under compressive cyclic loading is still not completely explored. The corresponding damage processes within the material structure are especially not entirely investigated. The application of acoustic measurement methods enables a better insight into the processes of the fatigue in concrete. Normal strength concrete was investigated under compressive cyclic loading with regard to the fatigue process by using acoustic methods in combination with other nondestructive measurement methods. Acoustic emission and ultrasonic signal measurements were applied together with measurements of strains, elastic modulus, and static strength. It was possible to determine the anisotropic character of the fatigue damage caused by uniaxial loading based on the ultrasonic measurements. Furthermore, it was observed that the fatigue damage seems to consist not exclusively of load parallel oriented crack structures. Rather, crack structures perpendicular to the load as well as local compacting are likely components of the fatigue damage. Additionally, the ultrasonic velocity appears to be a good indicator for fatigue damage beside the elastic modulus. It can be concluded that acoustic methods allow an observation of the fatigue process in concrete and a better understanding, especially in combination with further measurement methods. KW - Concrete KW - Fatigue KW - Damage evolution KW - Ultrasonic testing KW - Acoustic emission PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-541891 DO - https://doi.org/10.3390/ma15010341 SN - 1996-1944 VL - 15 IS - 1 SP - 341 EP - 355 PB - MDPI CY - Basel AN - OPUS4-54189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Pirskawetz, Stephan A1 - Thiele, Marc A1 - Löhr, Manuel A1 - Loewe, Anna A1 - Degener, Sebastian A1 - Herrmann, Ralf T1 - Acoustic emission for monitoring of fatigue damage in concrete elements of wind turbine towers N2 - Wind energy has become an important player in the energy transition in Germany. Towers of onshore wind turbines are often designed as hybrid structures: the lower part is made of prestressed concrete whereas the upper part is made of steel tubes. The tall structures are permanently subjected to cyclic loads. A research project of BAM as part of the joint project WinConFat - Structure focusses on the evelopment of techniques to monitor fatigue damage evolution in the concrete part. Results of a previous project show that a combination of ultrasonic and acoustic emission testing can give an indication for critical conditions near the end of the fatigue life of the concrete. In the ongoing project acoustic emission sensors have been installed at the base and at the transition piece between concrete and steel of a hybrid wind turbine tower. Beside of acoustic emission measurement the sensor spacing allows for measuring the concrete ultrasonic velocity along the circumference in both levels. Additional measurements like strain, temperature, inclination, or acceleration allow for comparison of environmental loads and change of acoustic properties of the concrete. The paper focusses on first acoustic measurements recorded since December 2023 in comparison to operating data of the wind turbine. T2 - EWGAE2024: 36th Conference of the European Working Group on Acoustic Emission CY - Potsdam, Germany DA - 18.09.2024 KW - Concrete fatigue monitoring KW - Acoustic emission KW - Ultrasound KW - Hybrid wind turbine tower PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612197 DO - https://doi.org/10.58286/30234 SN - 1435-4934 VL - 29 IS - 10 SP - 1 EP - 9 AN - OPUS4-61219 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weise, Frank A1 - Stelzner, Ludwig A1 - Recknagel, Christoph A1 - Pittrich, Tim A1 - Neugum, Tim A1 - Hering, Marcus A1 - Fiedler, Georg A1 - Thiele, Marc A1 - Simon, Patrick A1 - Maack, Stefan T1 - 63. DAfStb-Forschungskolloquium in der BAM - Themenblock 5: Bauteile und Bauwerke N2 - Ein weiterer Fokus des 63. DAfStb-Forschungskolloquiums (Tagungsband: DOI 10.26272/opus4-61338) lag auf den Bauteil- und Bauwerksuntersuchungen. Insbesondere wurde hier ein Einblick in die Forschungsaktivitäten in den BAM-Themenfeldern „Infrastruktur“ und „Energie“ gegeben. Thematisch wird dabei der Bogen von der Dauerhaftigkeit von Betonfahrbahndecken über die Extrembeanspruchung von Bauteilen und Bauwerken mittels Brand und Impact bis zum Bauwerksmonitoring und der Zustandsanalyse von Bestandsbauwerken gespannt. T2 - 11. Jahrestagung des DAfStb mit 63. Forschungskolloquium der BAM Green Intelligent Building CY - Berlin, Germany DA - 16.10.2024 KW - Dauerhaftigkeit von Betonfahrbahndecken KW - Alkali-Kieselsäurereaktion KW - Brand Impact KW - Bauwerksmonitoring PY - 2025 SN - 0005-9846 VL - 75 IS - 4 SP - 138 EP - 140 PB - concrete content UG CY - Schermbeck AN - OPUS4-63071 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -