TY - JOUR A1 - Epple, Niklas A1 - Schumacher, Thomas A1 - Murtuz, A. K. M. Golam A1 - Niederleithinger, Ernst A1 - Dusicka, Peter T1 - Combined passive and active ultrasonic stress wave monitoring of a full‑scale laboratory reinforced concrete bridge column subject to reverse‑cyclic lateral loading N2 - Effective monitoring of reinforced concrete structures requires techniques that detect early-stage material change and active, localized cracking. This study investigates a combined structural health monitoring approach using passive acoustic emission and active ultrasonic methods on a full-scale reinforced concrete bridge column subjected to reverse-cyclic lateral loading. Active monitoring, based on coda wave interferometry, was used to track changes in wave velocity and waveforms, while passive acoustic emission monitoring was used to detect crack activity. The instrumentation consisted of three embedded ultrasonic transducers and three surface-mounted acoustic emission sensors. The results show that active ultrasonic monitoring is most effective prior to visual damage, successfully detecting the onset of internal cracking via wave velocity decreases exceeding 0.4%, and distinguishing load-induced effects from permanent damage. However, its utility diminished in later stages of damage progression, as strong signal decorrelation hindered further data interpretation. Additionally, active US measurements allowed a comparison of damage severity in different parts of the column. Conversely, passive acoustic emission monitoring effectively tracked the formation of concrete cracks throughout the experiment, with distinct event clusters and high-amplitude signals (> 60 dB) confirming ongoing fracture processes in all damage states. This study confirms that combining these methods results in a more robust structural health monitoring strategy by leveraging their complementary strengths. Active techniques excel at tracking continuous material changes in early damage states, while passive methods are superior for detecting discrete cracking events as damage progresses. Importantly, both methods can utilize the same measurement equipment, enabling a cost-effective approach to continuous damage tracking. KW - Coda wave interferometry KW - Active ultrasonic monitoring KW - Acoustic emission KW - Structural health monitoring KW - Nondestructive evaluation PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-638689 DO - https://doi.org/10.1007/s13349-025-00996-w SN - 2190-5479 SP - 1 EP - 24 PB - Springer Nature AN - OPUS4-63868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Hille, Falk A1 - Fontoura Barroso, Daniel A1 - Niederleithinger, Ernst ED - Papadrakakis, M. ED - Fragiadakis, M. T1 - Monitoring of a prestressed bridge model byultrasonic measurement and vibration recordings N2 - The aim of this work is to improve the current structural health monitoring (SHM) methods for civil structures. A field experiment was carried out on a two-span bridge with a built-in un-bonded prestressing system. The bridge is a 24-metre long concrete beam resting on three bear-ings. Cracks were formed subsequently when a prestressing force of 350 kN was changed to 200 kN, so that different structural states could be demonstrated. The structural assessment of this reference bridge was accomplished by the non-destructive testing using ultrasonic devices and vibration measurements. The ultrasonic velocity variations were investigated by using the coda wave interferometry method. The seismic interferometry technique was applied to the vi-bration recordings to reconstruct the wave propagation field in the bridge. This investigation shows that the wave velocity is sensitive to the current structural state and can be considered as the damage indicator. Overall, the implementation of coda cave interferometry and seismic interferometry technique facilitates structural health monitoring (SHM) in civil engineering. T2 - COMPDYN 2021 8th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering CY - Online meeting DA - 28.06.2021 KW - Structural health monitoring KW - Non-destructive testing KW - Coda wave interferometry KW - Seismic interferometry KW - Ultrasonic measurement KW - Prestress PY - 2021 SP - 1 EP - 9 PB - European Community on Computational Methods in Applied Sciences (ECCOMAS) AN - OPUS4-52957 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lu, Xin A1 - Schukar, Marcus T1 - Humidity response analysis of optical fibers with hygroscopic coatings based on Lamé’s equations N2 - Optical fibers with hygroscopic coatings are widely used for humidity sensing, where the coating expands upon absorbing water, inducing strain in the fiber. This strain is then used to determine humidity. However, previous studies have oversimplified the strain generation process. A comprehensive three-dimensional model of the mechanical interaction between the coating and the fiber is built based on Lamé’s equations. An analytical expression for the induced strain is derived. The proposed model predicts larger humidity-induced strain compared to the reported ones, given the same Young’s modulus or coefficient of humidity expansion for the coating. Interestingly, the effect of coating thickness on strain response are quite similar for both methods. Experimental validation using fibers with a polyimide coating shows strong agreement with the theoretical predictions. T2 - 29th International Conference on Optical Fiber Sensors CY - Porto, Portugal DA - 26.05.2025 KW - Reflectometry KW - Distributed fiber sensing KW - Humidity sensors KW - Lamé’s equations KW - Optical fiber sensors KW - Structural health monitoring KW - Rayleigh scattering PY - 2025 SN - 978-1-5106-9188-9 DO - https://doi.org/10.1117/12.3060891 VL - 13639 SP - 1 EP - 4 PB - SPIE AN - OPUS4-63257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Munzke, Dorit A1 - Duffner, Eric A1 - Eisermann, René A1 - Schukar, Marcus A1 - Schoppa, André A1 - Szczepaniak, Mariusz A1 - Strohhäcker, J. A1 - Mair, Georg W. T1 - Monitoring of type IV composite pressure vessels with multilayer fully integrated optical fiber based distributed strain sensing N2 - We present the results of distributed fiber optic strain sensing for condition monitoring of a hybrid type IV composite fully wrapped pressure vessel using multilayer integrated optical fibers. Distributed strain sensing was performed for a total number of 252,000 load cycles until burst of the vessel. During this ageing test material fatigue could be monitored and spatially localized. Critical material changes were detected 17,000 cycles before material failure. Results have been validated by acoustic emission analysis. T2 - 12th International Conference on Composite Science and Technology (ICCST12) CY - Sorrento, Italy DA - 08.05.2019 KW - Hybrid composite pressure vessel KW - Distributed fiber optic sensing KW - Acoustic emission analysis KW - Structural health monitoring PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-516772 DO - https://doi.org/10.1016/j.matpr.2020.02.872 SN - 2214-7853 VL - 34 SP - 217 EP - 223 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-51677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Niederleithinger, Ernst A1 - Wang, Xin A1 - Epple, Niklas A1 - Schumacher, T. A1 - Ahmend, S. A1 - Klikowicz, P. ED - Yokota, H. ED - Frangopol, D. W. T1 - Ultrasonic coda wave monitoring of concrete structures: First experiences with large-scale experiments and real structures N2 - Ultrasonic monitoring, making use of the sensitivity of the coda of repeated transmission meas-urements to changes in stress, temperature, moisture, as well as localized or distributed damage, has gotten at-tention in structural health monitoring (SHM) research recently. Analysis methods such as coda wave inter-ferometry (CWI), including its nonlinear extension, have been shown to be able to measure ultrasonic wave velocity changes with a 1∙10-5 resolution, while indicators such as cross-correlation or cross-coherence have been used to distinguish between reversible and irreversible changes. Several small- and large-scale laboratory experiments have demonstrated that stress changes in structures can be captured or damage detected in a very early stage. The use of this technique for pre-warning before failure are currently under investigation, as well as detailed research on the physical causes and the connection between ultrasonic wave properties and materi-al/structural behavior. Recently, several of large-scale laboratory and real structures have been instrumented with embedded ultrasonic transducers to gather experience and evidence on how to use this technology in re-al-world applications. Preliminary results from installations on a new bridge, an existing bridge, a tunnel, a la-boratory earthquake test as well as a historic stadium in Germany, Poland, and the United States, respectively, are presented. Environmental influences (mainly temperature) and validation by load tests are discussed. KW - Coda wave interferometry KW - Structural health monitoring KW - Ultrasound KW - Concrete KW - Bridges PY - 2021 SN - 978-0-367-23278-8 DO - https://doi.org/10.1201/9780429279119-345 SP - 2525 EP - 2531 PB - Taylor & Francis CY - London, UK AN - OPUS4-54168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Bernauer, F. A1 - Igel, H. A1 - Hadziioannou, C. A1 - Niederleithinger, Ernst T1 - Real-time bridge monitoring using ultrasonic techniques combined with six-component (6-C) measurements N2 - This study aims to develop a real time structural health monitoring method by ultrasonic tests combined with advanced six component (6C) translation and rotation measurements. Conventionally, the investigation of the velocity and acceleration response in the translation direction is used to obtain the eigenfrequencies of structures. Recently the measurement of rotation has been considered to fully characterize the dynamic behavior of structures. This research undertakes the evaluation of a novel 6C sensor (IMU50-iXblue) with components originally developed for navigation for the purpose of bridge monitoring. However, as for all vibration recordings, there is a certain influence of environmental conditions (mainly temperature) which may affect evaluation and the results of structural assessment. We propose applying the cross-correlation function to the 6C ambient vibration signals to reconstruct wave propagation and using coda wave interferometry (CWI) to obtain internal velocity variation from waveforms. A field experiment on a large-scale prestressed concrete bridge model is presented. To verify that we are able to identify the pre-stress loss even in presence of temperature effects, we perform measurements in two different scales: the ultrasonic and output-only, vibration measurements. The change in the structural properties due to the pre-stress loss should be detected by the pulse velocity change. The results reveal both the performance and advantages of ultrasonic techniques and the capabilities of 6C sensors. To conclude, the application of CWI to wave signals contributes to a comprehensive assessment for bridge monitoring. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Structural health monitoring KW - Ultrasonic KW - Coda wave interferometry PY - 2022 SP - 1 EP - 10 AN - OPUS4-55660 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man A1 - Niederleithinger, Ernst T1 - Real time bridge monitoring using ultrasonic techniques combined with six component (6-c) measurements N2 - This study aims to develop a real-time monitoring method for the structural performance by ultrasonic testing in combination with six-component (6-C) translation and rotation measurements. So far, the recordings of the velocity and acceleration response in the translation direction have been used to obtain the eigenfrequencies of structures. Recently, measurement of rotation has been used to fully characterize the dynamic behavior of structures. In this research, 6-C sensors consisting of a three-component rotational seismometer and a three-component broadband seismometer are evaluated for their suitability for bridge monitoring. Since changes in environmental conditions such as temperature during vibration recordings affect the structural evaluation results, cross-correlation function is applied here to the 6-C ambient vibration signals to reconstruct the wave propagation on the one hand, and coda wave interferometry (CWI) is applied to obtain the internal velocity variation from waveforms on the other hand. In field tests on a large-scale prestressed concrete bridge model, it was verified whether the prestress loss can also be determined in presence of temperature effects. For this purpose, measurements were performed in two scales, ultrasonic and output-only vibration measurements. The change in structural properties due to the prestress loss should be detected by the pulse velocity change. The results demonstrate both the performance and advantages of ultrasonic techniques and the capabilities of 6-C sensors. Thus, the application of CWI to wave signals can contribute comprehensively to bridge monitoring. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - 6-C vibration signals KW - Coda wave interferometry KW - Cross-correlation function KW - Prestressed bridge KW - Structural health monitoring KW - Ultrasonic PY - 2022 AN - OPUS4-55646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karapanagiotis, Christos A1 - Heimann, Jan A1 - Duffner, Eric A1 - Charmi, Amir A1 - Schukar, Marcus A1 - Hashemi, Seyedreza A1 - Prager, Jens T1 - Towards predictive maintenance of hydrogen pressure vessels based on multi-sensor data N2 - In this paper, we report on a sensor network for structural health monitoring (SHM) of Type IV composite overwrapped pressure vessels (COPVs) designed for hydrogen storage. The sensor network consists of three different SHM sensing technologies: ultrasonic guided waves (GW), acoustic emission (AE) testing, and distributed fiber optic sensors (DFOS). We present an experimental setup for a lifetime test, where a COPV is subjected to cyclic loading. Data from all sensors are collected and centrally evaluated. The COPV failed after approximately 60,000 load cycles, and the sensor network proved capable of detecting and localizing the damage even before the failure of the COPV. This multi-sensor approach offers significantly more channels of information and could therefore enable a transition from costly and time-consuming periodic inspections to more efficient and modern predictive maintenance strategies, including artificial intelligence (AI)-based evaluation. This not only has a positive effect on operational c KW - Ffiber optic sensors KW - Acoustic emission KW - Guided waves KW - Hydrogen KW - Digital twin KW - Structural health monitoring PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618948 DO - https://doi.org/10.58286/30513 SP - 1 EP - 8 PB - NDT.net AN - OPUS4-61894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wosniok, Aleksander A1 - Schukar, Marcus A1 - Woody, Paul A1 - Wang, Bin A1 - Breithaupt, Mathias A1 - Kriegsmann, Andreas T1 - Distributed fiber optic strain sensing for structural health monitoring of 70 MPa hydrogen vessels N2 - We report on the development and testing of 70 MPa hydrogen pressure vessels with integrated fiber optic sensing fibers for automotive use. The paper deals with the condition monitoring of such composite pressure vessels (CPVs) using the optical backscatter reflectometry (OBR) applied for a distributed fiber optic strain sensing along fully integrated polyimide-coated single-mode glass optical fiber (SM-GOF). The sensing fibers were embedded into the vessel structure by wrapping them over the polymer liner during the manufacturing process of the carbon fiber reinforced polymer (CFRP). Detecting local strain events by the integrated fiber optic sensors can be an opportunity for monitoring the material degradation of CPVs under static and cyclic loading. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Fiber optic sensor KW - Distributed strain sensing KW - Composite pressure vessel KW - Structural health monitoring KW - Fiber-reinforced plastics PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603105 SP - 1 EP - 8 PB - NDT.net AN - OPUS4-60310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Xin A1 - Chruscicki, Sebastian A1 - Schukar, Marcus A1 - Münzenberger, Sven A1 - Krebber, Katerina T1 - Application of Intensity-Based Coherent Optical Time Domain Reflectometry to Bridge Monitoring N2 - Although distributed fiber sensing techniques have been widely used in structural health monitoring, the measurement results of bridge monitoring, particularly under destructive testing, have rarely been reported. To the best of our knowledge, this paper is the first report of distributed vibration measurement results, which we obtained during a three-day destructive test on an abolished bridge. A coherent optical time domain reflectometry (COTDR) was used to acquire the vibration information while the bridge was being sawed. The obtained signal was analyzed in time and frequency domain. Some characteristics of the sawing-induced vibration were retrieved by the short-time Fourier transform; the vibration exhibited several high frequency components within the measured range up to 20 kHz and all the components appeared in the same time slot. Some unexpected signals were also detected. Thorough analysis showed that they are quite different from the sawing-induced vibration and are believed to originate from internal damage to the bridge (probably the occurrence of cracks). KW - Destructive testing KW - Structural health monitoring KW - Distributed fiber sensing KW - Distributed acoustic sensing PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-547451 DO - https://doi.org/10.3390/s22093434 VL - 22 IS - 9 SP - 3434 PB - MDPI AN - OPUS4-54745 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos A1 - Heimann, Jan A1 - Duffner, Eric A1 - Charmi, Amir A1 - Schukar, Marcus A1 - Hashemi, Seyedreza A1 - Prager, Jens T1 - Towards predictive maintenance of hydrogen pressure vessels based on multi-sensor data fusion and digital twin modeling N2 - Hydrogen pressure vessels are among the most essential components for reliable hydrogen technology. Under current regulations, a mostly conservative strategy is employed, restricting the usage time of hydrogen pressure vessels without providing information on the real remaining lifetime. During the service life, pressure vessels are inspected periodically. However, no established method that can provide continuous monitoring or information on the remaining safe service life of the vessel. In this paper, we propose a sensor network for Structural Health Monitoring (SHM) of hydrogen pressure vessels where data from all sensors are collected and centrally evaluated. Specifically, we integrate three different SHM sensing technologies namely Guided Wave ultrasonics (GW), Acoustic Emission testing (AT), and distributed Fiber Optic Sensing (FOS). This integrated approach offers significantly more information and could therefore enable a transition from costly and time-consuming periodic inspections to more efficient and modern predictive maintenance strategies, including Artificial Intelligence (AI)-based evaluation. This does not only have a positive effect on the operational costs but enhances safety through early identification of critical conditions in the overall system in real-time. We demonstrate an experimental set-up of a lifetime test where a Type IV Composite Overwrapped Pressure Vessel (COPV) is investigated under cyclic loading instrumented with AT, FOS, and GW methods. We acquired data from the sensor network until the pressure vessel failed due to material degradation. The data collected using the three different SHM sensor technologies is planned to be evaluated individually, using data fusion, and AI. In the future, we aim to integrate the measurement setup into a hydrogen refueling station with the data stream implemented into a digital signal processing chain and a digital twin. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Acoustic emission KW - Ultrasonic guided waves KW - Fiber optic sensors KW - Hydrogen KW - Pressure vessels KW - Structural health monitoring KW - Machine learning PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602764 UR - https://www.ndt.net/search/docs.php3?id=29702 SP - 1 EP - 8 PB - NDT.net AN - OPUS4-60276 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Karapanagiotis, Christos A1 - Schukar, Marcus A1 - Breithaupt, Mathias A1 - Duffner, Eric A1 - Ulbricht, Alexander A1 - Prager, Jens A1 - Krebber, Katerina T1 - Structural health monitoring of hydrogen pressure vessels using distributed fiber optic sensing N2 - We report on distributed fiber optic sensing-based monitoring of hydrogen composite overwrapped pressure vessels (COPV) to simultaneously increase the operational lifespan and mitigate maintenance costs. Our approach represents, to the best of our knowledge, the first application of distributed fiber optic sensing for COPV Type IV monitoring, where the sensing fibers are attached to the surface, rather than integrated into the composite material. Specifically, we attach an optical fiber of 50 m to the pressure vessel's surface, covering both the cylindrical and dome sections. We note that our fiber optic sensing technique relies on swept wavelength interferometry providing strain information along the entire length of the optical fiber with high spatial resolution even at the millimeter scale. When the vessel is pressurized, the sensing optical fiber shows a linear strain response to pressure at every position along the fiber. After thousands of load cycles, the vessel finally fails with the optical fiber detecting and precisely localizing the damage in the vessel’s blind dome area. Furthermore, we discuss the potential of state-of-the-art signal processing methods and machine learning for advancing predictive maintenance. This could reduce the number of regular inspections, mitigate premature maintenance costs, and simultaneously increase the vessel’s remaining safe service life. We believe that the structural health monitoring of hydrogen pressure vessels with fiber optic sensors can enhance trust in hydrogen technology contributing to the energy transition in the future. T2 - 11th European Workshop on Structural Health Monitoring CY - Potsdam, Germany DA - 10.06.2024 KW - Hydrogen KW - Fiber optic sensors KW - Composites KW - Machine learning KW - Structural health monitoring PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602731 UR - https://www.ndt.net/search/docs.php3?id=29701 SP - 1 EP - 7 PB - NDT.net AN - OPUS4-60273 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Karapanagiotis, Christos A1 - Breithaupt, Mathias A1 - Duffner, Eric A1 - Schukar, Marcus T1 - Real-time monitoring of hydrogen composite pressure vessels using surface-applied distributed fiber optic sensors N2 - In this paper, we report to the best of our knowledge for the first time on continuous real-time monitoring of composite overwrapped pressure vessels (COPVs) designed for hydrogen storage using surface-applied distributed fiber optic sensors (DFOS). We conducted continuous and real-time DFOS measurements during pressure cycling tests consisting of periodic pressure fluctuations between 20 bar and 875 bar, with a rate of 5 cycles min−1. During pressure cycling, the DFOS system measured strain changes, that under normal operating conditions were linearly correlated to changes in pressure. To detect and quantify damage-related anomalies, we trained a simple regression model to predict strain from pressure data and used the difference between predicted and measured values as a damage indicator. With our approach, the DFOS system not only detected and localized the damage but also continuously tracked its evolution in real time under dynamic pressure conditions. Furthermore, unlike previous studies where optical fibers were embedded within the composite structure, we applied them on the COPV surface, reducing both implementation cost and time while eliminating the need to modify the COPV manufacturing process. Based on our results, we are confident that DFOS can enhance safety and facilitate the transition from time-consuming periodic inspections to more efficient, machine learning-based predictive maintenance. KW - Fiber optic sensors KW - Hydrogen KW - Structural health monitoring KW - Pressure vessels KW - Predictive maintenance PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-627644 DO - https://doi.org/10.1088/2515-7647/adb9ac SN - 2515-7647 VL - 7 IS - 2 SP - 2 EP - 10 PB - IOP Publishing Ltd CY - Bristol, UK AN - OPUS4-62764 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - ridge Monitoring by Ultrasonic Coda Wave Interferometry N2 - The built infrastructure ages and requires regular inspection and, when in doubt, monitoring. To ensure that older concrete bridges showing signs of deterioration can be used safely, several innovative monitoring tools have been introduced, including but not limited to optical, fiber-optic, or acoustic emission techniques. However, there are gaps in the portfolio. A sensing technique that covers a wide range of damage scenarios and larger volumes, while still being sensitive and specific, would be beneficial. For about 15 years, research has been conducted on ultrasonic monitoring of concrete structures that goes beyond the traditional ultrasonic pulse velocity test (PV test), mostly using a very sensitive data evaluation technique called coda wave interferometry. At BAM we have developed sensors and instrumentation specifically for this method. We have instrumented a 70-year-old, severely damaged prestressed concrete bridge in Germany in addition to a commercial monitoring system. We have now collected data for almost 3 years. We can show that we can provide information about the stress distribution in the bridge. We have also been able to confirm that there has been no significant additional damage to the bridge since the installation. T2 - ISNT NDE 2023 CY - Pune, India DA - 07.12.2023 KW - Coda wave interferometry KW - Structural health monitoring KW - Ultrasound KW - Concrete KW - Bridges PY - 2023 AN - OPUS4-59346 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Liao, Chun-Man T1 - Assessment of prestress loss in a large-scale concrete bridge model under outdoor condition N2 - The presentation shows that subtle variations in coda wave velocity can capture minor temperature effects, offering a good understanding of how a outdoor prestressed concrete structure responds to environmental conditions over time. Ultimately, this work contributes to development of more comprehensive and resilient structural health monitoring strategies for prestressed concrete infrastructure. T2 - EVACES 2025 CY - Porto, Portugal DA - 02.07.2025 KW - Coda wave interferometry KW - Damage detection KW - Prestress loss KW - Seismic interferometry KW - Structural health monitoring PY - 2025 AN - OPUS4-64211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prager, Jens T1 - Technological and Regulatory Constraints on the Use of Structural Health Monitoring - Our Experience with SHM for Hydrogen Pressure Vessels N2 - Structural Health Monitoring (SHM) is seen as a key component of NDT 4.0. The aim is to replace labour- and cost-intensive periodic inspections with integrated sensor technology and automated data evaluation, and to increase the operational safety and reliability of critical components. Although SHM is already being used to monitor infrastructure components, approaches for technical structures and components have not yet left the laboratory scale, despite intensive efforts. This is particularly the case for aircraft components, pipelines and components in the chemical and process industries. As part of a publicly funded joint project, BAM has attempted to supplement or replace the legally required periodic inspection of high-pressure hydrogen storage tanks with SHM. With regard to a real laboratory "hydrogen refuelling station", different sensor concepts were applied to type IV pressure vessels and the vessels were subjected to accelerated ageing by pressure cycling. The applied monitoring methods were validated against different failure mechanisms. The contribution presents the results of the project and discusses the specific challenges of using SHM approaches in practice. In addition to describing the technological challenges of replacing periodic inspections with SHM, the talk addresses the legal aspects for the operation of pilot plants and real laboratories. As artificial intelligence and machine learning methods are favoured for signal processing, evaluation and assessment of SHM measurement data, the impact of the European AI Act as the first legal framework for AI is also discussed. T2 - SYSINT 2025 CY - Bremen, Germany DA - 04.06.2025 KW - Pressure vessels KW - Structural health monitoring KW - Ultrasound PY - 2025 AN - OPUS4-64526 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schackmann, Oliver A1 - Márquez Reyes, Octavio A1 - Memmolo, Vittorio A1 - Lozano, Daniel A1 - Prager, Jens A1 - Moll, Jochen A1 - Kraemer, Peter T1 - Intelligent damage detection in composite pressure vessels under varying environmental and operational conditions N2 - Despite proven approaches available in the literature, structural health monitoring by ultrasonic guided waves under varying environmental and operational conditions is still challenging. The use of machine learning approaches is discussed in this work, considering the complex problem of experimental damage detection under varying load conditions in a composite overwrapped pressure vessel for hydrogen storage. Specifically, unsupervised methods originally developed for image and time series classification are combined with ensemble voting to conceive reliable damage detection technique. This enables the effective combination of the predictions of multiple transducer pairs, even with a limited number of strong individual classifiers. A performance demonstration of the technique is presented using a real damage scenario dataset. T2 - IEEE 12th International Workshop on Metrology for AeroSpace (MetroAeroSpace) CY - Napoli, Italy DA - 18.06.2025 KW - Guided ultrasonic waves KW - Structural health monitoring KW - Artificial intelligence KW - Hydrogen storage PY - 2025 SN - 979-8-3315-0152-5 DO - https://doi.org/10.1109/MetroAeroSpace64938.2025.11114628 SN - 2575-7490 SP - 608 EP - 613 AN - OPUS4-64894 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Xin A1 - Christensen, J. A1 - Thomas, P. A1 - Failleau, G. A1 - Eisermann, R. A1 - Hicke, Konstantin A1 - Krenek, S. T1 - Fiber artefact for performance evaluation of time domain distributed fiber sensor interrogators N2 - Distributed fiber sensing (DFS) is a powerful tool for structural health monitoring (SHM), allowing continuous and seamless measurements of temperature and strain along the fiber. The spatial accuracy of a DFS interrogator, as a key parameter of the system, is vital for precisely locating structural perturbations or defects. Its evaluation and calibration methods however attract little attention. A fiber optic artefact based on a fiber loop is developed to evaluate distance accuracy and signal quality for both self-developed and commercial sensing systems based on Rayleigh, Raman, and Brillouin scattering effects, respectively. The measured distance is corrected to remove the influence of the pulse width. Additionally, the obtained SNRs are compared for different loop trips and pulse widths, assisting to assess signal quality for SHM applications. KW - Structural health monitoring KW - Distributed fiber sensing KW - Distributed temperature sensing KW - Fiber artefact KW - Spatial correction PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648966 DO - https://doi.org/10.1088/1361-6501/ae214e VL - 36 IS - 11 SP - 1 EP - 10 PB - IOP Publishing Ltd CY - Bristol, UK AN - OPUS4-64896 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lu, Xin A1 - Königsbauer, Korbinian A1 - Hicke, Konstantin T1 - Improved phase retrieval method for system simplification or fading suppression in interferometer-based φOTDR systems N2 - Phase sensitive optical time domain reflectometry (φOTDR) systems based on different types of interferometers for phase retrieval typically require two or three photodetectors to record the outputs from the interferometer. A novel signal processing principle is proposed for phase retrieval by taking the difference between two outputs as the quadrature component and reconstructing the in-phase component via Hilbert transformation of the Q component for IQ demodulation. Thus, only one balanced photodetector or two standard photodetectors are need, reducing system complexity and data volume. This principle can also be used to suppress fading effect for the traditional three-detector φOTDR systems by selecting optimal phases across detector pairs. Experiments with a φOTDR systems based on an imbalanced Mach-Zehnder interferometer validate the feasibility of this method and demonstrate a high fading suppression of about 90%. KW - Phase retrieval KW - Distributed fiber sensing KW - Structural health monitoring PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-652630 DO - https://doi.org/10.1364/OE.580984 SN - 1094-4087 VL - 33 IS - 26 SP - 54733 EP - 54746 PB - Optica Publishing Group AN - OPUS4-65263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Johann, Sergej A1 - Baensch, Franziska A1 - Sturm, Patrick A1 - Tiebe, Carlo A1 - Pötschke, Samuel A1 - Lay, Vera ED - Holl, H. T1 - HF RFID-based measurement comparison for method optimization in M2 concrete and alkali-activated mortars N2 - Monitoring of repositories for radioactive waste requires techniques which can be applied long-term under harsh conditions. In this work, the reliability and suitability of materials and a capacitive sensor for measuring relative humidity are investigated, which are to be embedded in the special concrete components for the closure structures of underground repository. Preliminary tests with accelerated aging of the materials used, validation of the sensors under difficult conditions, investigations of the surfaces after aging by pH 14 solution, defined exposure of the sensors in a climatic chamber and the microscope images are discussed. The results will be used for further development and optimization of the RFID based sensor systems which can be applied to monitor the condition of different building structures without cabling. T2 - 37th Danubia - Adria Symposium on Advances in Experimental Mechanics CY - Linz, Austria DA - 21.09.2021 KW - Alkali-activated mortars KW - Passive sensor interface KW - RFID KW - Structural health monitoring KW - Smart structures PY - 2022 DO - https://doi.org/10.1016/j.matpr.2022.03.465 SN - 2214-7853 VL - 62 IS - 5 SP - 2571 EP - 2576 PB - Elsevier CY - Amsterdam AN - OPUS4-54697 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Jägle, Eva A1 - Tuladhar, Rujika A1 - Niederleithinger, Ernst A1 - Epple, Niklas A1 - Sanchez Trujillo, Camila Andrea A1 - Gehlen, Christoph A1 - Timothy, Jithender J. T1 - Evaluation of ultrasonic signals collected from laboratory concrete specimens: Preprocessing and analysis with coda wave interferometry N2 - Efficient maintenance of infrastructure relies on monitoring and assessment of its condition. New technologies and methods thereby enable a deeper understanding of the materials used and of the structures built. Coda Wave Interferometry (CWI) is currently explored for continuous monitoring of reinforced concrete structures as well as material testing. This ultrasound-based method is sensitive to even small material alterations and therefore suitable for the detection of initial damage stages. Herein, a step-by-step procedure for the evaluation of ultrasonic signals with CWI methods is presented. The described procedure is proposed for ultrasonic signals collected with embedded ultrasonic transducers with a center frequency of 50 kHz to 70 kHz from prism-shaped concrete specimen with dimensions of 400 mm x 100 mm x 100 mm. The raw ultrasonic signal, preprocessing and CWI analysis are described and influences of parameters within the analysis are discussed. The presented procedure allows systematic and comparable analysis of ultrasonic signals generated with similar conditions and therefore contributes to the application of CWI methods for structural health monitoring and material testing. KW - Ultrasound KW - Concrete KW - Coda wave interferometry KW - Structural health monitoring PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-656027 DO - https://doi.org/10.1016/j.mex.2026.103811 SN - 2215-0161 VL - 16 SP - 1 EP - 19 PB - Elsevier B.V. AN - OPUS4-65602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -