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- Distributed acoustic sensing (4)
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Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (12)
- 8.6 Faseroptische Sensorik (12)
- 3 Gefahrgutumschließungen; Energiespeicher (5)
- 3.5 Sicherheit von Gasspeichern und Gefahrguttanks (5)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (3)
- 2 Prozess- und Anlagensicherheit (1)
- 2.4 Prüfung und Bewertung von Explosivstoffen/Pyrotechnik (1)
- 2.5 Konformitätsbewertung Explosivstoffe/Pyrotechnik (1)
- 7 Bauwerkssicherheit (1)
- 7.4 Baustofftechnologie (1)
A novel method for transformer vibration monitoring using intensity-based distributed acoustic/vibration sensing (DAS/DVS) is presented. Fibre optic sensors were fully integrated into an oil-filled medium voltage distribution transformer. Opencircuit in-situ measurements were carried out using a single and three-phase supply with an electrical power of up to 30 kVA.
Spectral analysis of the mechanical vibrations were performed by measuring the frequency response of the transformer using plain fibre- and transducer-based DVS approaches. The results were compared with the spectra of a microphone mounted on the outside of the transformer housing and the electrical measurements on the high voltage side. Using the fibre optic DVS based monitoring we were able to detect changes in operating power and frequency. Further it could be shown, that it is possible to identify anomalous behaviour such as electrical/mechanical noise sources using the determined vibration spectra.
We present a preliminary investigation on distributed humidity monitoring during the drying process of concrete based on an embedded polymer optical fiber (POF). The water dissipated into the POF changes several properties of the fiber such as refractive index, scattering coefficient and attenuation factor, which eventually alters the Rayleigh backscattered light. The optical time Domain reflectometer (OTDR) technique is performed to acquire the backscattered signal at the wavelengths 650 nm and 500 nm, respectively. Experimental results show that the received signal increases at 650 nm while the fiber attenuation factor clearly increases at 500 nm, as the concrete dries out. In the hygroscopic range, the information retrieved from the signal change at 650 nm agrees well with the measurement result of the electrical humidity sensors also embedded in the concrete sample.
We investigated the capabilities of long period gratings (LPG) in single-mode microstructured polymer optical fibre (mPOF) for humidity sensing. For that mPOF LPGs were exposed to different humidity levels
at a constant temperature of 30°C in a climate chamber. During the long term tests, which took up several weeks, the humidity was changed in several steps while mPOF LPG wavelength and fibre attenuation were measured.
We also measured the water uptake of mPOF in environment with different relative humidity.
Retroreflektierende Materialien besitzen die Eigenschaft, Licht in Beleuchtungsrichtung wieder zurück zu reflektieren. Mit der Anwendung derartiger Produkte ist ein erheblicher Gewinn an Sicherheit in Gefahrensituationen angestrebt. Ausgehend von der Definition und experimentellen Bestimmung des Spezifischen Rückstrahlwertes wird ein Überblick zur Spezifikation in Normen bezüglich seiner Winkelkombinationen gegeben. Der Fokus des Beitrages liegt auf der Bestimmung der Erweiterten Ergebnisunsicherheit entsprechend der GUMMethodik mittels Modell als Funktion dieser Winkelkombinationen. Weiter untersetzende Untermodelle werden beschrieben und die damit verbundenen Fehleranteile diskutiert.
Monitoring of composite pressure vessels using surface applied distributed fiber optic sensors
(2024)
In this paper, we report on surface-applied distributed fibre optic sensors for monitoring composite pressure vessels designed for hydrogen storage. Previous reports have revealed that integrating optical fibres within vessel composite structures effectively enables the monitoring of structural behavior throughout their lifetime.
However, integrating optical fibres during the manufacturing process is complex and time-consuming. Therefore, we aim to simplify this process by attaching the optical fibres to the vessel’s surface. This method is significantly more timeefficient than the integration process and can be applied to any vessel. Our results demonstrate that surface-applied fibre optic sensors can detect and precisely localise damage.
Additionally, signs of damage can be recognised even before the damage occurs. Predictive maintenance using fibre optic sensors could reduce premature maintenance costs and periodic inspections while increasing safety and extending the vessel’s useful service life. The role of machine learning in predictive maintenance is also discussed.
The number of in-operation composite pressure vessels is increasing, partly due to their attractiveness for on-board compressed gas storage and transport applications. A possible way to maintain the highest safety levels is through the structural health monitoring of the composite cylinders. Here, the use of fiber optic sensors appears to be a promising approach. However, the integration of the optical fibers into the composite structure of a pressure vessel has been shown to be challenging. In this study, insights on the embedding of optical fibers in the composite structure under industrial conditions are provided. A protection concept for the ingress and egress of the optical fibers is presented. Finally, the results from destructive slow burst tests are evaluated, showing no clear trend in the impact of the embedded optical fibers on the performance of composite pressure vessels.
