Filtern
Dokumenttyp
Schlagworte
- Notch (2)
- Bending (1)
- Crack propagation (1)
- Damage (1)
- Electrodynamic shaker (1)
- Elektrodynamisch (1)
- Envrionmental simulation (1)
- Ermüdung (1)
- Fatigue (1)
- Gefüge (1)
- Kurze Risse (1)
- Lebensdauer (1)
- Life prediction (1)
- Microstructure (1)
- Periodische Lastwechselbeanspruchung (1)
- Prüfung (1)
- Railway rail (1)
- Resonance testing (1)
- Risslängenbestimmung (1)
- Risstiefenbestimmung (1)
- Schienentestkörper (1)
- Service loading (1)
- Service loading fatigue (1)
- Shaker (1)
- Short cracks (1)
- Simulation (1)
- Specimen size (1)
- Two-degree-of-freedom system (1)
- Ultraschall (1)
- VHCF (1)
- Variable frequency (1)
Schwing- und Betriebsfestigkeitsuntersuchungen an Eisenbahnschienen UIC 60 unter Wechselbiegung
(2009)
Die Forschungsstelle BAM führte Untersuchungen zur Ausbreitung von Querrissen im Bauteil Schiene in zehn Einstufen und Betriebsfestigkeitsversuchen durch. Es wurden die Lebensdauer und die Rissentwicklung einer durch einen außermittigen Kerb vorgeschädigten Schiene des Profils 60 E1 (260) ermittelt. Die gekerbten Schienen zeigen ein zu aus der Literatur bekannten Schienen mit starken Head Checks vergleichbares Verhalten. Der Rissfortschritt der Bauteilversuche wird mit Ergebnissen an SE(B)-Proben verglichen. Die Ableitung der Belastungsfunktion aus realen Schienenbelastungen für die 3-Punkt-Biegung unter Wechsellast und die Versuchsbedingungen werden als Basis für die Validierung von Berechnungsverfahren hinreichend beschrieben.
This paper deals with life prediction by observation and simulation of short fatigue cracks in cyclically loaded smooth and notched specimens made of 0.15 wt-% carbon steel SAE1017. The measured crack behaviour was simulated in a microstructural environment. Reference tests under constant amplitude loading allowed to determine model parameters and hence a reasonable life prediction by simulation resulted even for service loading. Short crack behaviour was a measurable property for damage also to compare smooth and notched specimens.
Fatigue testing in the VHCF ränge requires testing machines with increased frequencies. However, application of energy-saving resonance testing leads to a linkage between test frequency and specimen Parameters. The frequency ränge and the available forces of the testing machine are limiting possible specimen dimensions.
Electrodynamic shakers combine test frequencies up to 4000 Hz with forces in the kN range. Thus, a relatively wide range of tests is possible which allows studying the influence of specimen size on VHCF behaviour.
Electrodynamic shakers as well as the respective Computer control Systems and Vibration measurement techniques are well established in scientific and technical applications. We present results of a first study of VHCF testing on electrodynamic shakers conducted at BAM. Test frequency, specimen size and stress levels have been varied. One goal is to balance the needs of materials testing with the Standard test Systems of environmental Simulation to provide a powerful and flexible tool for very high cycle fatigue testing. Further investigation to optimize the technique is required.
The development of procedures to calculate the service life of railway rails requires test results which describe the damage of rails thus affording their validation. Within the DEUFRAKO integrated project NOVUM, ten rail specimens were tested under constant and variable amplitude loads to investigate the propagation of lateral cracks and to ascertain the service life. The test conditions were based on real rail loading and were used in the 3-point-bending test frame under alternating stress. An eccentric notch was applied as pre-arranged damage in the 60 E1 (260) rail specimens. The notched rails showed a similar behaviour like rails with strong head checks damaged by rolling contact fatigue.