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 - Lay, Vera A1 - Baensch, Franziska A1 - Skłodowska, Anna A1 - Fritsch, Tobias A1 - Stamm, Michael A1 - Prabhakara, Prathik A1 - Johann, Sergej A1 - Sturm, Patrick A1 - Kühne, Hans-Carsten A1 - Niederleithinger, Ernst T1 - Multi–sensory Monitoring and Non–destructive Testing of New Materials for Concrete Engineered Barrier Systems N2 - The crucial part of nuclear waste storage is the construction of sealing structures made of reliable, safe and well–understood materials. We present an extended analysis of long-term multi–sensory monitoring and non–destructive testing (NDT) inspection of two laboratory specimens aiming at potential materials for sealing structures for nuclear waste repositories. Specimens with a volume of 340 litres made from newly developed alkali–activated materials (AAM) and established salt concrete (SC) were analysed using embedded acoustic emission and wireless radio-frequency identification (RFID) sensors, ultrasonic echo imaging, active thermography, and X–ray computed tomography. The monitoring analysis showed lower heat of reaction and 50% less acoustic emission events in AAM compared to SC. However, due to the surface effects of the AAM material, the number of acoustic emission events increased significantly after approximately two months of monitoring. Subsequently performed NDT inspections reliably located embedded sensors and confirmed the absence of major cracks or impurities. The presented laboratory results show the feasibility and potential of comprehensive NDT monitoring and inspection to characterise cementitious and alternative materials as well as the need for multi–parameter long–term monitoring. Thus, our study demonstrates that tailored NDT investigations will help to develop safe sealing structures for nuclear waste repositories. KW - Radioactive waste KW - Barrier KW - Concrete KW - AAM KW - Non-destructive testing PY - 2024 DO - https://doi.org/10.3151/jact.22.516 SN - 1347-3913 VL - 22 IS - 9 SP - 516 EP - 529 PB - Japan Concrete Institute AN - OPUS4-61461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Hofmann, Detlef A1 - Sturm, Patrick A1 - Stamm, Michael A1 - Niederleithinger, Ernst T1 - Multi-sensory monitoring and ultrasound for quality assurance at underground sealing structures N2 - Within the safety concepts of underground disposal sites of nuclear waste, engineered barriers play an important role. As these sealing structures have high demands concerning integrity, we aim at advancing the available construction materials, monitoring, and inspection techniques within the project SealWasteSafe. A specifically developed alkali-activated material is compared to classical salt concrete. A comprehensive multi-sensory monitoring scheme is used at 150-340 l specimens to monitor setting and hardening of both materials. All sensors are demonstrated to resist the highly alkaline environments. Besides cabled and wireless temperature and humidity of the materials, strain variations using fibre optic sensors and acoustic emissions are recorded over periods of at least 28 days, partly for more than eight months. After hardening of the specimens, further nondestructive evaluations using ultrasonic echo and thermographic measurements are conducted. Preliminary results proof the suitability of the tested sensors and clearly highlight differences between the tested materials. Particularly, the newly developed alkali-activated material shows lower acoustic emission activity indicating less cracking activity. Additionally, unique ultrasonic methods will enable better images of potential internal objects and cracks at in-situ sealing structures. A largescale ultrasonic system is optimised to reliably detect objects at a depth exceeding 9 m while still obtaining a good resolution. Modelling studies show the potential of further increasing the distance between individual transducer arrays. Additionally, a new ultrasonic borehole probe using phased arrays allowing for beam focussing is constructed and tested. Laboratory measurements at a halfcylindrical concrete specimen coincide well with the previous modelling. In total, the presented safe materials, detailed monitoring approaches and ultrasonic quality assurance methods will help to obtain safe sealing structures within salt as a host rock. The concepts can partly be transferred to sealing structures in alternative host rocks and will also be valuable for non-nuclear waste repositories. T2 - NDE NucCon CY - Espoo, Finland DA - 25.01.2023 KW - SealWasteSafe KW - Engineered barriers KW - Monitoring KW - Embedded sensors KW - Ultrasonic imaging PY - 2023 SP - 2 EP - 10 AN - OPUS4-56928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Chaudhuri, Somsubhro A1 - Krankenhagen, Rainer A1 - Lapšanská, Ivana A1 - Stamm, Michael T1 - WTB-IRT: Modelling and Measurement of Thermal Contrast in Wind Turbine Rotor Blades (WTBs) N2 - The rapid growth of wind energy infrastructure over the past two to three decades has led to an urgent need for advanced non-destructive testing (NDT) methods—both for newly installed wind turbine blades (WTBs) and for ageing components nearing the end of their service life. Among emerging techniques, passive infrared thermography (IRT) offers a promising solution by enabling contactless, time-efficient inspection based on naturally occurring thermal variations. The effectiveness of passive IRT depends on the presence of sufficient thermal contrast to distinguish surface features, subsurface structures, and defects. To better understand the possibility of obtaining such contrast in composite structures such as WTBs, a controlled study was carried out on a blade section exposed to programmed temperature transients in a climate chamber. Infrared measurements were recorded, and the thermal behaviour of the specimen was simulated using finite element models (FEM) in COMSOL Multiphysics 6.3. Although direct validation is limited by measurement uncertainties and transient effects, the comparison provides insight into the capabilities and limitations of FEM in replicating real-world thermal behaviour. This paper focuses specifically on the challenges related to the modelling approach. T2 - 18th International Workshop on Advanced Infrared Technology and Applications (AITA 2025) CY - Kobe, Japan DA - 15.09.2025 KW - Thermography KW - Wind energy KW - Wind turbine rotor blades KW - Windenergie Anlage Rotorblätter KW - FEA PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-642308 DO - https://doi.org/10.3390/proceedings2025129015 VL - 129 IS - 1 SP - 1 EP - 5 PB - MDPI CY - Basel AN - OPUS4-64230 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - The KI-VISIR Reference Dataset: A Compilation of Thermal and Visual Inspection Data for Quantifying Leading Edge Rain Erosion N2 - This presentation introduces thermography (thermal imaging) as a key method for non-destructive testing (NDT) of wind turbine rotor blades. By leveraging solar heating and aerodynamic effects, passive thermography detects internal defects, delaminations, and surface issues like leading edge erosion. We discuss field measurements, the role of AI/Machine Learning (LATODA) for automated defect classification, and its importance for improving O&M efficiency and lifetime extension in the wind energy sector. T2 - WindEurope Annual Event 2025 CY - Copenhagen, Denmark DA - 08.04.2025 KW - Thermography KW - Wind Turbine Blades KW - AI KW - NDT KW - KI-VISIR PY - 2025 AN - OPUS4-64721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Einführung thermografischer Methoden in die Ermüdungsprüfung unter Laborbedingungen sowie bei Ganzblatt-Rotorblattprüfungen N2 - Der Vortrag der Bundesanstalt für Materialforschung und -prüfung (BAM) stellt die Einführung und Anwendung thermografischer Methoden zur Ermüdungsprüfung und Ganzblatt-Rotorblattprüfung vor. Die BAM, tätig in Forschung, Prüfung und Beratung, trägt zur technischen Sicherheit bei und unterstützt die Energiewende. Die Abteilung 8.3 "Thermographic Methods" arbeitet an der Forschung, Entwicklung und Anwendung thermografischer Prüf- und Überwachungstechniken. Passive Thermografie ist eine bildgebende Messung der Oberflächentemperatur, die Informationen über das Innere von Bauteilen liefert. Durch Nutzung von Sonneneinstrahlung und Temperaturschwankungen können auch große Strukturen wie Rotorblätter geprüft werden. Thermische Inspektionen visualisieren Temperaturunterschiede, die durch Material-, Struktur-, Aerodynamik- und Oberflächeneigenschaften sowie Reibungswärme entstehen. Bei rotierenden Rotorblättern wird die Thermografie eingesetzt, um Strömungsphänomene (laminar/turbulent), Oberflächendefekte (z.B. Regen-Erosion) und innere Defekte zu erkennen. Ein Schlüsselprojekt ist die AI-gestützte Bildklassifizierung (LATODA) von über 1200 Roh-Infrarotbildern für die Mangeldetektion. Ziel ist die Entwicklung von zuverlässigen, automatisierten, robotergestützten Verfahren, um Schäden schnell zu erkennen und so Effizienzverluste (AEP-loss) zu vermeiden und die Lebensdauer von Windenergieanlagen zu verlängern. T2 - Mitgliederversammlung des BWE- Sachverständigenbeirates CY - Hannover, Germany DA - 5.9.2025 KW - Thermografie KW - Wind KW - Rotorblätter KW - Inspektion PY - 2025 AN - OPUS4-64719 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stamm, Michael T1 - Thermografische Ferninspektion von Windenergieanlagen im Betrieb –� Potenziale und Herausforderungen N2 - Rotorblätter zählen zu den kostenintensivsten Komponenten von Windenergieanlagen in Bezug auf Wartung und Ausfallzeiten. Mit der zunehmenden Blattlänge – aktuell bis zu 115 m – steigen auch die Anforderungen an effektive Inspektionsmethoden. Die Bundesanstalt für Materialforschung und -prüfung (BAM) entwickelt hierfür eine passive thermografische Ferninspektion vom Boden aus, die die klassische visuelle Prüfung durch Industriekletterer ergänzen oder perspektivisch ersetzen soll. Feldmessungen und Laborexperimente belegen das Potenzial dieser Technik, sowohl strömungsbedingte thermische Signaturen als auch strukturelle Anomalien innerhalb der Rotorblätter zu erfassen. Eine besondere Herausforderung liegt in der Trennung dieser überlagerten Effekte sowie in der eingeschränkten Kenntnis der inneren Blattstruktur aufgrund fehlender Designdaten. Um die Methode zur Marktreife zu führen, sind Fortschritte in der Bildverarbeitung, etwa durch eine patentierte Differenzbildung, erforderlich. Der Beitrag stellt die zugrunde liegende Messtechnik, Ergebnisse einer groß angelegten Feldstudie mit 30 Anlagen sowie die identifizierten physikalischen Einflussgrößen (Strömung, Struktur, Emissivität) vor und gibt einen Ausblick auf die nächsten Entwicklungsschritte. T2 - Thermo25 CY - Munich, Germany DA - 12.11.2025 KW - Thermography KW - Wind Turbine Blades KW - Wind KW - Rotorblätter PY - 2025 AN - OPUS4-64718 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chaudhuri, Somsubhro A1 - Krankenhagen, Rainer A1 - Lapšanská, Ivana A1 - Stamm, Michael T1 - Modeling Temperature Responses of a Wind Turbine Blade Section Under Climate Chamber Conditions – Part 1: Challenges for FEM Simulations N2 - The rapid expansion of wind energy infrastructure over the past 20–30 years has led up to a situation where advanced non‐destructive testing (NDT) technologies are the need‐of‐the‐hour, not only for new wind turbine blades (WTBs) that are being installed, but also for older infrastructure which is reaching their designed lifetime. NDT technologies that improve both the quality as well as reduce the time required for the inspection are sought after, and one such example is passive infrared thermography (IRT). For passive IRT to provide significant information/insight into the integrity of the WTB, there needs to exist certain thermal contrast to both visualize and distinguish between features in WTB. These features could be surface features, subsurface structure or defects. The temperature variations due to air temperature fluctuations and the sun assist (passively) to obtain the necessary thermal contrast. To better understand the thermal response of composite structures such as WTBs, a validation study was conducted using a WTB section subjected to controlled temperature transients within a climate chamber, without external irradiation. Infrared measurements were recorded using a thermographic camera, and the same specimen was modeled using finite element methods (FEM) in COMSOL Multiphysics. While a direct validation of the simulation is limited due to transient and unmeasured variables in the experimental data, qualitative comparison provides valuable insight into the applicability of FEM for predicting thermal behavior in passive IRT scenarios. This article represents the first part of a two‐part study, focusing on the FEM modeling approach and associated challenges. The second part will address the experimental investigation in more detail, with an emphasis on thermal contrast behavior under varied transient conditions. KW - Finite element modeling KW - Non- destructive testing KW - Passive infrared thermography KW - Thermal contrast KW - Wind turbine blades PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655330 DO - https://doi.org/10.1002/we.70102 SN - 1095-4244 VL - 29 IS - 3 SP - 1 EP - 14 PB - Wiley AN - OPUS4-65533 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -