Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (18)
- Beitrag zu einem Tagungsband (9)
- Vortrag (4)
- Forschungsbericht (1)
Schlagworte
- Degradation (7)
- Behälterversagen (6)
- Consequences (5)
- Druckbehälter (4)
- Explosion (4)
- Auswirkungsbetrachtung (3)
- Berstprüfung (3)
- Betriebssicherheit (3)
- Composite (3)
- Lastwechselempfindlichkeit (3)
Organisationseinheit der BAM
- 3 Gefahrgutumschließungen; Energiespeicher (6)
- 3.0 Abteilungsleitung und andere (5)
- 8 Zerstörungsfreie Prüfung (4)
- 2 Prozess- und Anlagensicherheit (3)
- 2.1 Sicherheit von Energieträgern (3)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (3)
- 2.2 Prozesssimulation (2)
- 7 Bauwerkssicherheit (2)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (2)
- 8.6 Faseroptische Sensorik (2)
Eingeladener Vortrag
- nein (4)
Im Rahmen einer Bachelorarbeit zum Thema „Untersuchungen an Bremsleitungsabschnittsreparaturen“ zwischen der HTW Berlin und der TÜV Rheinland Kraftfahrt GmbH wurden in Zusammenarbeit mit der Bundesanstalt für Materialforschung und -prüfung (BAM) Berstdruckprüfungen durchgeführt. Im Rahmen der Kooperation sollte untersucht werden, inwiefern Reparaturmaßnahmen an beschädigten Bremsleitungsabschnitten sicherheitstechnisch unbedenklich sind, auch in Bezug auf die Verwendung unterschiedlicher auf dem Markt erhältlicher Bremsleitungsmaterialien.
Fibre-reinforced plastics (FRP) especially carbon-fibre-reinforced polymer (CFRP) and glass-fibre-reinforced polymer (GFRP) are commonly used materials in high pressure vessels and storage units for automotive and aerospace purposes. Optical fibres are suitable to be integrated or directly applied to the surface of FRP components. Using optical fibres it is possible to monitor the distributed strain profiles and changes within the fatigue life of a pressure vessel to ensure the operational safety. Within artificial ageing experiments we used swept wavelength interferometry (SWI) based distributed strain sensing for the monitoring of commercial high-pressure composite cylinder. This artificial ageing was performed using test conditions of 503bar pressure load (service pressure 300 bar) and 89 °C for 100 h. The polyimide coated optical fibres were glued to the surface externally in circumferential and axial direction. Using distributed strain sensing (DSS) material expansion of over 0.5% were monitored with sub-centimetre spatial resolution. Within the circumferential direction we observed up to 10 % local fluctuation compared to the median strain caused by inhomogeneous material expansion, which could cause local material fatigue. In addition, we determined material degradation manifested itself as localized remaining material expansion and/or contraction. Results have been validated by other non-destructive methods like digital strip projection.
Within a current research project at the Federal Institute for Materials Testing and Research (BAM), the degradation process of composite pressure vessels is studied to be able to give more accurate lifetime predictions in future. The presented research is based on type III pressure vessels consisting of an aluminium tank which is fully wrapped with carbon fibre reinforced plastics. Focus is set on the analysis of residual stresses which are induced into the pressure vessel during manufacturing process in order to increase high cycle fatigue. However, with increasing lifetime residual stress conditions do change. To be able to measure and monitor stress conditions, the application of a non-destructive measurement method is aspired.
In this paper, potential of an experimental modal analysis is worked out to capture and monitor aging and degradation effects in pressure vessels. With the presented method, information about changes in residual stress can be obtained via an analysis of the modal parameters. To realize an application, first, a finite element simulation is used to prove and evaluate potential capability and validity. In the following, a test bench is set up and successively optimized in its accuracy and efficiency. Sensitivity of the applied measurement technique is experimentally ascertained trough the measurement of several prestress modified pressure vessels. Finally, experimental results are interpreted and evaluated with the help of numerically gained findings.
15 identical off-the-shelf propane cylinders (m = 11 kg liquid propane) were underfired. The infrared Radiation of the Explosion, that occurred in the aftermath of the vessel failure, was recorded using four bolometers. These measurements are compared with an estimation of the Maximum intensity gained by an Analysis of the Video data, an Extended Version of the Stefan-Boltzmann law and a BLEVE model.
Flüssige und komprimierte Gase sind in Deutschland, Europa und der Welt vielfältig als alternative Kraftstoffe im Einsatz. Diese werden unter teilweise hohem Druck in robusten Behältern an Bord gespeichert. Ein Versagen des Treibstoffbehälters im Schadensfall sollen verschiedene Sicherheitseinrichtungen, auch bei einem eventuell unfallbedingt auftretenden Fahrzeugbrand, verhindern. Sind diese Sicherheitseinrichtungen unfallbedingt beschädigt oder liegen die Belastungen dieser Einrichtung außerhalb ihres Auslegungsbereichs, ist ein Versagen des Behälters dennoch möglich. Dadurch kann es zur Bildung eines explosionsfähigen Brennstoff-Luft-Gemischs mit den entsprechenden Folgen für Fahrgäste, Einsatzkräfte und Umfeld kommen. Die Bundesanstalt für Materialforschung und -prüfung (BAM) untersucht im Forschungsprojekt "CoFi-ABV" mit umfangreichen zerstörenden Versuchsreihen im Realmaßstab die Folgen des unfallbedingten Versagens von Behältern für alternative Kraftstoffe und Maßnahmen zur Reduktion dieser Folgen im Rahmen einer ganzheitlichen Auswirkungsbetrachtung. Dieser Beitrag ist der Start einer Reihe und soll die Problemstellung sowie die Projektinhalte umfassend erläutern.
In continuation of a preceding test series involving sole LPG vehicle tanks, three passenger cars equipped with identical toroidal steel LPG tanks were set on fire. The tanks were installed in the space normally reserved for the spare tyre, in the car boot. No safety device was installed on the tank, in order to force critical failure of the cylinder. Two of the cars were equipped with a tank filled with liquefied propane to a level of 20 % (5.3 kg), the third one was filled completely (25.5 kg). The partially filled tanks failed critically within a time period of more than 20 min after the initiation of the fire. The fully-filled tank did not rupture; the propane was released continuously through a small leak that appeared during the fire. Comprehensive equipment was used to procure measurement data, enabling an analysis of potential consequences and hazards to humans and infrastructure within the vehicle surroundings. The inner status of the tank (pressure, temperature of the liquid phase and the steel casing), the development of the fire (temperature inside and around the vehicle) and the pressure induced in the near-field in case of tank rupture were recorded. The results were analysed in detail and compared against the data gained in tests involving sole, but identical LPG tanks.
Small, mobile propane gas vessels are widely spread and comprise additional hazards in case of a surrounding, intensive fire. The aim of the presented work is to holistically investigate the potential consequences of failure of these off-the-shelf propane gas vessels in case of an absence or malfunction of safety devices. In order to generate a statistically valid dataset, a total of 15 identical propane gas bottles without pressure relief device, each containing m = 11 kg of liquid propane, were underfired in horizontal position. For each selected fire type (wood fire, petrol pool fire, propane gas fire), five vessels were tested under identical conditions. Next to extensive camera equipment including a high-speed camera, systems to record the internal pressure of the gas cylinder, the resulting shock wave overpressure (three positions) and the flame and vessel temperature (three + three positions) during the underfiring were used. Also the unsteady, highly dynamical thermal radiation caused by the explosion of the expanding gas cloud was logged. The fragments were georeferenced and weighed after each test. The experiments prove the failure of all the gas cylinders at a burst pressure of pb = [71 … 98 bar] with a fragmentation into up to seven parts (average: four objects) and a subsequent explosion of the expanding vapour after mixing with the surrounding air. The overpressure measured in the close-up range (distance to the cylinder d = 5 m) resulting from the shockwave caused by the cylinder burst was up to pmax = 0.27 bar, which can potentially lead to significant injuries to humans and damage to building structures and infrastructure, especially in connection with the explosion and the resultant thermal radiation. The distance covered by the fragments after the failure was up to r = 260 m; 47% of the fragments hit the ground more than r = 50 m away from the position of failure.
Composite materials show a degradation of properties depending on Service life. This creates the necessity to find tailored methods to determine strength and residual strength of composite cylinders. The determination can be done e.g. by load cycles tests. The result needs a Statistical assessment for the precise description of strength. Especially the Statistical assessment of load cycle strength properties has a high uncertainty. It is unclear if a Log-Normal distribution, a WEIBULL distribution or others, describe the scatter behaviour of residual strength properties correctly. Distribution functions aim at approximating the frequency of occurrence of residual load cycle strength for high survival rates. An assumption has to be found and confirmed to prevent overestimation of reliability.