THESIS ON FRETTING FATIGUE IN RAILWAY AXLES

New stopping criteria for crack detection during fatigue tests of railway axles HOME New stopping criteria for crack detection during fatigue tests of railway axles. For machines with rotating axle, the temperature of the axle and variations on the center of the axle position and on the applied load are continuously monitored using sensors. Conclusion The rotor shaft of a wind turbine and its typical loads are clarified. E is the Young’s modulus, Of and ef are material strength parameters and b and c are material fitting parameters. The software used was FLEX5.

Results obtained from analytical analysis could help to make a damagetolerant design, and to optimize the safety and planning of maintenance [2]. These fatigue limits are: The experimental results showed that the strength changes of the front axle after strengthening under low-amplitude loads was almost proportional to hardness, but it was inverse ratio for the transmission gear. 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. 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.

Further more, the typical features of wear or friction and iron oxide was observed on the wheel seat near the crack area.

Exemplary load time series of the bending moment MYNR Since the shaft is rotating during turbine operation, it is subjected to a rotating bending moment. An iterative model to predict the fatigue strength of a component subjected to fretting wear has first been developed by Paysan Stress concentration factors are defined in order fatiguw take into account the reduced fatigue strength of the component.

thesis on fretting fatigue in railway axles

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. The orange line shows the superposition of both bending moments on the rotor railwayy at the position of the main bearing.

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Analysis of Transverse Cracks Forming in a Railway Axle

In order to find out the effects of tempering process on properties of axle steel, the thesis analyzes the change trend of properties of LZ20Mn2 axle steel pipe with variation of tempering temperature.

Later, a signal conditioner MMF, model M32 was also installed and a data acquisition device Keithley was used to send data to a computer via a USB link. Fatigue tests can be performed using test machines in which the axle rotates or more frequently on Sincotec resonance test machines feetting. Real axles and similar smooth bigger specimens were tested with respect to fatigue limits.

Fatigue tests can be performed using test machines in which the axle rotates or more frequently, using Sincotec resonance test machines. Probabilistic transferring relations are deduced by the data from material, to similar specimens, and then to structures at the fatigue limit phase. Cumulative frequency distribution of nominal bending stresses at the bearing seat of the rotor shaft blue and green line are presented qualitatively.

New stopping criteria for crack detection during fatigue tests of railway axles

The reason of surface hardness changes could be due to that the microstructure thssis material was improved after being strengthening under low-amplitude loads below the fatigue limit. Surface defect is the main form of axle failure.

thesis on fretting fatigue in railway axles

Vibration, Fatigue tests, Fatigue crack, Railway Engineering. They defined the fretting-fatigue-damage-parameter FFDP: Experimental setups In order to assess the fatigue strength of rotor theesis and the emergence of fretting wear, two test benches have been designed.

This emphasizes, that at least in this case, fretting fatigue was more critical for the component. The two stopping criteria for the tests were if the number of cycles reached or if a crack 4 a b Fig. Stochastic irregularities of the track are considered in the dynamic axlrs and the load history acted on wheelset is obtained.

New stopping criteria for crack detection during fatigue tests of railway axles – PDF Free Download

Accompanying full scale and 1: In practice this could likely result in the need for an theiss fit which would be difficult to realize. The shape of the cumulative frequency distribution of the stresses reflects the particular characteristics of the different load components. By the means of a rainflow counting algorithm the load time series are transferred to a cumulative frequency distribution of loads, extrapolated to 20 years of turbine operation and afterwards analytically converted into a distribution of nominal bending stresses at the bearing seat.

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A prediction of finite life is not intended. According to the calculations, any crack with that length or above will lead to a failure of the component within the year life span. In the case of the rotor shaft, the principle stress is set equal to the bending stress.

thesis on fretting fatigue in railway axles

Journal of Lanzhou Railway Institute. New stopping criteria for crack detection during fatigue tests of railway axles HOME New stopping criteria for crack detection during fatigue tests of railway axles. A precise and reliable NDT technique is necessary to ralway cracks in the axle.

The Society of Materials Science, Japan.

Effect of Understress on Fretting Fatigue Crack Initiation of Press-Fitted Axle

Adewusi, Wavelet analysis of vibration signals of an overhang rotor with a propagating transverse crack, Journal of Sound and Vibration 5 — Non-destructive testing of railway truck axles. For theais decomposition level of 5, a total of 25 packets, or values of energy, were obtained for each signal. This paper deyls with the phenomenon oWfcetting fatigue; on the rotor shaft of c wind turbine at the shrink fit o!

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