According to Herrmann et al. For rotating axle tests, there are alarm levels for the displacement of the center of the axle, axle temperature, and variation of the load applied. Under rotation the rollers will introduce a tangential force onto the wave-shaped inner ring, forcing it to rotate on the shaft. According to Zeise the endurance limit of an assembly subjected to fretting is predicted by excluding crack initiation. Intemational Joumal of Fatigue. This one has been developed and assembled by the University of Applied Sciences in Hamburg.
The fatigue limit values required for railway axles are shown in table 1. As a service to our customers we are providing this early version of the manuscript. This seems reasonable when considering that cracks from fretting fatigue will at a certain length start growing under Mode I, dominated by the principle stress, in a direction perpendicular to the contact surface. Therefore, a critical state of crack initiation is identified by monitoring the local frictional shear stresses during the simulation of fretting development. Detail of the dimensions of the specimens used for the fatigue tests An experimental modal analysis was performed to determine resonant frequencies using accelerometers and a dynamometric hammer.
For axles broken by tests 1 5 Test Speed RPM Load kN Stopping reason Number of cycles 1 Threshold values reached 2 Maximum number of cycles 3 Threshold values reached Table 3 Results of fatigue tests where Test 1 and 3 fatogue bold resulted in broken axles a b Fig. The sensitivity of the rotor shaft for growing rai,way that nucleate at the bearing seat is investigated and available approaches of fretting fatigue prediction for shaft-hub and shaft-bearing connections are presented.
Life assessment of dovetail joints between blades and discs in aero-engines. Journal of Materials 5, November 29, Released: Based on the NSOFT software, the fatigue life of axles is predicted by applying appropriate fatigue life prediction methods. The axle was supported at three fatihue in the center and at the two extremes.
Fatigue cracks are initiated in press-fitted parts such as the wheel and brake disk seats of the axle. Cracks were detected fregting the basis of the measurements exceeding the threshold values for the displacement of the center of the axle, the temperature, and the variation in the load applied.
Yet, according to Zeise et al. This inference was made as the phenomenon was not observed for the axle that remained intact.
Along with the trend of ggowing rotor diametecs and hub heights, the lobds on the rotor shaft and the main bearing of awind turbine are continuously increasing. This change in frequency behavior could therefore be used for crack detection. Their application to the rotor shaft of a wind turbine is assessed and a validation on a full scale and a 1: A shear stress based critical-plane criterion of multiaxial fatigue failure for design and life prediction.
An overview is presented in the following section. For both types of test machines, fatigue tests aim to check if a crack appears in an axle within loading cycles, thus it is necessary to establish stopping thesi in case a crack appears during the test.
Transferring of fatigue behavior is investigated from material to structure for Chinese railway LZ50 axle carbon steel.
Analysis of Transverse Cracks Forming in a Railway Axle
However, this concept and also the approach of critical bearing load, aim on excluding an initial crack respectively critical relative movements. These results show that fretting fatigue at the bearing seat can be critical for the life of the rotor shaft, when high stress concentration is acting on the fretted surface.
It was concluded that, due to surface presure and the existence of stress concentration, which the wheel and axle interference fit resulted in, wear abrasion and fretting fatigue initiated fatigue crack. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NDT Non-Destructive Testing is useful for the defect detection of rolling stock because it can be used to detect defects in many invisible parts.
The results show that the strength and hardness of LZ20Mn2 axle steel drop gradually and its toughness and plasticity are increased when tempering temperature goes up.
Stress concentration factors are defined in order to take into account the reduced fatigue strength of the component. Signs of fretting at the bearing seat axlex rotor shafts from different manufacturers At the same time a more light-weight design thhesis the rotor shaft is fatige.
Engineering Failure Analysis Received Date: On the full scale test bench six shafts from forged steel will be tested. Fatigue tests can be performed using test machines in which the axle rotates or more frequently, using Sincotec resonance test machines.
The decomposition levels were analyzed from 5 to 9. Notch factor model In design guidelines like FKMthe dimensioning of certain distinguished shaft-hub connections is specified. The changes in the trend values in this example began prior to those changes that were related to the harmonics of the rotation speed of the axle.
Analysis of Transverse Cracks Forming in a Railway Axle
In terms of a conservative approach, the main bearing is assumed to sit at the shaft shoulder. Structural probabilistic S-N curves are obtained by the material fatigue behavior to extend the transferring relations to entire fatigue life range.
Non-destructive testing of railway truck axles.