8.6 Faseroptische Sensorik
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Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (237)
- 8.6 Faseroptische Sensorik (237)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (28)
- 3 Gefahrgutumschließungen; Energiespeicher (26)
- 8.4 Akustische und elektromagnetische Verfahren (20)
- 7 Bauwerkssicherheit (17)
- 2 Prozess- und Anlagensicherheit (16)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (16)
- 7.4 Baustofftechnologie (14)
- 1 Analytische Chemie; Referenzmaterialien (13)
- 1.4 Prozessanalytik (13)
- 3.5 Sicherheit von Gasspeichern (11)
- 6 Materialchemie (10)
- 2.1 Sicherheit von Energieträgern (9)
- 3.2 Gefahrguttanks und Unfallmechanik (8)
- 2.4 Prüfung und Bewertung von Explosivstoffen/Pyrotechnik (7)
- 2.5 Konformitätsbewertung Explosivstoffe/Pyrotechnik (7)
- 3.0 Abteilungsleitung und andere (7)
- 9 Komponentensicherheit (7)
- 9.6 Additive Fertigung metallischer Komponenten (7)
- 5 Werkstofftechnik (6)
- 6.7 Materialsynthese und Design (6)
- 7.2 Ingenieurbau (5)
- 8.0 Abteilungsleitung und andere (5)
- 6.6 Physik und chemische Analytik der Polymere (4)
- 5.4 Multimateriale Fertigungsprozesse (3)
- 8.5 Röntgenbildgebung (3)
- 5.3 Polymere Verbundwerkstoffe (2)
- 7.1 Baustoffe (2)
- 5.0 Abteilungsleitung und andere (1)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (1)
Schäden an Rohrleitungen können zu hohen Umweltbelastungen und wirtschaftlichen Schäden führen. Um die dauerhafte Verfügbarkeit der Infrastruktur zu gewährleisten, wird im Rahmen des Projekts AGIFAMOR an der Bundesanstalt für Materialforschung und -prüfung (BAM) erprobt, inwiefern das Verfahren der verteilten akustischen faseroptischen Sensorik (Distributed acoustic sensing - DAS) zur kontinuierlichen Überwachung von Rohrleitungen verwendet werden kann. Neben der DAS werden erprobte Verfahren der zerstörungsfreien
Prüfung wie Schallemissionsanalyse (SEA) und Beschleunigungssensoren eingesetzt. An dieser Stelle soll detailliert auf die unterschiedlichen Messverfahren und deren spezifischen Einsatz im Rahmen des Projektes eingegangen werden.
Schäden an Rohrleitungen können zu hohen Umweltbelastungen und wirtschaftlichen Schäden führen. Um die dauerhafte Verfügbarkeit der Infrastruktur zu gewährleisten, wird im Rahmen des Projekts AGIFAMOR an der Bundesanstalt für Materialforschung und -prüfung (BAM) erprobt, inwiefern das Verfahren der verteilten akustischen faseroptischen Sensorik (Distributed acoustic sensing – DAS) zur kontinuierlichen Überwachung von Rohrleitungen eingesetzt werden kann. Neben der DAS werden erprobte Verfahren der zerstörungsfreien Prüfung wie Schallemissionsanalyse (SEA) und Beschleunigungssensoren eingesetzt. An dieser Stelle soll detailliert auf die Hauptschadensursachen an Rohrleitungen, den Versuchsstand zur mechanischen Belastung von Rohren sowie die Möglichkeiten zu Untersuchungen im Realmaßstab eingegangen werden.
The feasibility study „AGIFAMOR. Ageing infrastructures – distributed acoustic monitoring of pipes” is an interdisciplinary research project at BAM internally financed from 2015 to 2018. Therefore, the quite young fibre optic sensing technology of distributed acoustic sensing (DAS) was investigated to possibly be extended towards a global condition monitoring system for pipelines operating in real time.
DAS is a highly dynamic fibre optic sensing technology based on the method of coherent optical time domain reflectometry (C-OTDR). DAS allows capturing strain changes in the range of kHz. For the experimental work, the most suitable application yielding an optimum sensitivity was proven by wrapping a standard single-mode silica fibre around the pipe.
The DAS sensitivity was investigated regarding the detection of 1) incidents that initiate propagation of acoustic waves in the pipe wall, 2) changes inside the pipeline causing altered flow and 3) damage development in the pipe wall. Therefore, several testing setups in laboratory as well as in real scale were realized. For comparison purposes, experiments were accompanied by acoustic emission analyses and by measurements with accelerometers.
DAS was found to be very sensitive to gas ignition and its propagation across the pipe. Furthermore, the ability of DAS to detect and localize acoustic signals associated with pipeline leakage was demonstrated. The detection of crack formation and propagation within the pipe wall by means of DAS was studied during bending tests on several pipe segments, but was not proven so far with certainty. As expected, these studies turned out as the most difficult challenge due to the random occurrence and transient nature of microscopic damage phenomena.
Acoustic emission testing
(2018)
Feasibility study: Continuous monitoring of pipes using distributed acoustic and fibre optic sensors
(2018)
The feasibility study „AGIFAMOR. Ageing infrastructures – distributed acoustic monitoring of pipes” is an interdisciplinary research project at BAM internally financed from 2015 to 2018. Therefore, the quite young fibre optic sensing technology of distributed acoustic sensing (DAS) was investigated to possibly be extended towards a global condition monitoring system for pipelines operating in real time.
DAS is a highly dynamic fibre optic sensing technology based on the method of coherent optical time domain reflectometry (C-OTDR). DAS allows capturing strain changes in the range of kHz. For the experimental work, the most suitable application yielding an optimum sensitivity was proven by wrapping a standard single-mode silica fibre around the pipe.
The DAS sensitivity was investigated regarding the detection of 1) incidents that initiate propagation of acoustic waves in the pipe wall, 2) changes inside the pipeline causing altered flow and 3) damage development in the pipe wall. Therefore, several testing setups in laboratory as well as in real scale were realized. For comparison purposes, experiments were accompanied by acoustic emission analyses and by measurements with accelerometers.
DAS was found to be very sensitive to gas ignition and its propagation across the pipe. Furthermore, the ability of DAS to detect and localize acoustic signals associated with pipeline leakage was demonstrated. The detection of crack formation and propagation within the pipe wall by means of DAS was studied during bending tests on several pipe segments, but was not proven so far with certainty. As expected, these studies turned out as the most difficult challenge due to the random occurrence and transient nature of microscopic damage phenomena.
Current capabilities for full-scale field testing are highly resource intensive. Reliable small-scale experiments are an effective alternative. Characterization of the dynamic response and damage of RC elements to scaled blast loads was investigated in scaled-down field experiments. Spatially resolved information on the dynamic structural response using distributed fiber optic acoustic sensing (DAS) and acceleration as well as blast loading by piezoelectric pressure sensors.
A safety or security related assessment of explosions, accidental and intentional scenarios alike, often necessitate performance of replication-tests. Such test results are necessary to clarify the causes within the scope of forensic investigations. To gain important insights into the behavior of structures and materials under such loading, field tests may also be performed in accordance with different test standards. To determine the resistance of building-structures after explosions, estimation of the residual load-bearing capacity in addition to the assessment of dynamic structural response and damage to the building components is important. In most cases an evaluation of structural integrity is based only on the visual damage, resulting in an overestimation of the residual capacity.
The Bundesanstalt für Materialforschung und -prüfung (BAM) operates the Test site for Technical Safety (TTS) on an area measuring about 12 km2 in the Federal State of Brandenburg for execution of true-to-scale explosion tests. At the TTS, building component testing was performed to assess the suitability of different non-destructive testing methods to characterize the dynamic structural response and damage resulting from the detonation of high explosives.
Different blast-loading scenarios were realized by varying the net explosive mass and the standoff distance with all scenarios representing a near-field detonation. The test object was a reinforced concrete wall 2 m high, 2.5 m wide and 20 cm thick, fixed at both vertical edges. The dynamic loading of the wall was characterized with 8 piezoelectric pressure sensors flush-mounted on the front surface, thus measuring the reflected pressures from the shock wave. The tests were conducted with the aim of characterizing the global behavior of the wall under dynamic shock loading and the resulting local damage pattern, respectively. High speed digital image correlation was implemented in combination with multiple acceleration sensors to observe the rear surface of the wall to chart the dynamic deflection during the loading and to determine the residual deformation after the loading had ceased. In addition, one test specimen was instrumented with fiber optic sensor cables, both fixed to the rebars and embedded in the concrete-matrix, respectively. Firstly, these sensors were interrogated during the blast test by a distributed acoustic sensing (DAS) device using a particularly high sampling rate to measure the shock-induced vibrations in the structure with high temporal resolution. This delivers information on dynamics of compression and tension cycles from within the structure. Secondly, the local damage-pattern emerging during the series of blasts was determined via distributed fiber optic strain sensing (DSS) by interrogating the embedded fiber optic sensors with a high spatial resolution DSS device after each blast. This enabled the characterization of non-visual damage to the structure, in particular with regard to the formation of localized cracks in the concrete matrix. The DSS was further complimented by a structure-scanner based on ultrasonic measurements.
Our contribution describes this new test approach in detail. Results of the three datasets, namely dynamic shock loading, global behavior of the test object and the local damage pattern will be presented. The suitability of the implemented measurement methods will be discussed in combination with the challenges in their application for technical safety evaluation of building components under explosive loading.