THESIS ON FRETTING FATIGUE IN RAILWAY AXLES

Multiaxial models Multiaxial models try to take into consideration the time-variant and non-proportional nature of contact stresses. Most of the researches related to rotating machinery diagnosis agrees with the use of vibration signals, because they contain valuable information about the failures [10—12]. 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. For the considered rotor shaft assembly and the cumulative frequency distribution of the stresses, the threshold value for crack growth is reached at a crack length of 1. An iterative model to predict the fatigue strength of a component subjected to fretting wear has first been developed by Paysan

For a crack with a length of 1. According to Maiwald , bearings that are subjected to large bending moments and axial loads will experience not only an axial slip between shaft and inner ring of the main bearing, but also a tangential creeping movement of the inner ring on the shaft. And SEM was used to observe and analyze the fracture. Therefore, a critical state of crack initiation is identified by monitoring the local frictional shear stresses during the simulation of fretting development. As a service to our customers we are providing this early version of the manuscript.

Analysis of Transverse Cracks Forming in a Railway Axle

Their application do the rotor shaft of a wind turbine is assessed and a validation on a full scale and a 1: Static and fatigue strength of the axles are analyzed as well as the raillway of the interference fit between wheel and axle on the contact pressure. Position of strain gauges during the static test was detected before this was achieved. Zhu, Research progress in mechanism and protection methods of material fretting fatigue.

Although the specific loading and exact geometry of that broken shaft is unfortunately not available to the authors, it is assumed that the turbine was subjected to loads during operation which were clearly above frettung design loads. The main bearing of such an arrangement is typically a spherical roller bearing and the gearbox is elastically mounted.

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

Vibration, Fatigue tests, Fatigue crack, Railway Engineering. According to Babbickthe oxide particles accumulate in the fitting gap and lead to a modified stress distribution, a change in dimension and position accuracy, surface pitting, the formation of grooves and cracks. Finding the ideal strategy: One setup is in full scale, the other one in 1: 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.

E is the Young’s modulus, Of and ef are material strength parameters and b and c are material fitting parameters.

thesis on fretting fatigue in railway axles

Their application to the rotor shaft of a wind turbine is assessed and a validation on a full scale and a 1: 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 thewis direction perpendicular to the contact surface. Fatigue tests of railway axles. Stochastic irregularities of the track are considered in the dynamic simulation and the load history acted on wheelset is obtained.

Analysis of Transverse Cracks Forming in a Railway Axle

Multiaxial models Multiaxial models try to take into consideration the time-variant and non-proportional nature of contact stresses. VDI Verlag, 21 – Adewusi, Wavelet analysis of vibration signals of an overhang rotor with a propagating transverse crack, Journal of Sound and Vibration 5 — The same test procedure will be carried out for the 1: A precise and reliable NDT technique is necessary to detect cracks in the axle.

The decomposition levels were analyzed from 5 to 9. During the test, the shaft’s condition is monitored by fretring large number of strain gages.

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thesis on fretting fatigue in 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. Reznicek, Fatigue tests of railway axles, Procedia Engineering 2 — This one has been developed and assembled by the University of Applied Sciences in Hamburg. The use of one of the latest developments of the Wavelet Transform WTthe Wavelet Packets Transform WPTallows detecting a crack to be detected a many cycles before the conventional methods.

thesis on fretting fatigue in railway axles

Eventually the crack becomes long enough and the crack growth is dominated by the principle stress. The use of one of the latest developments of the Wavelet Transform, the Wavelet Packets Transform, allows a crack to be detected many cycles before fretring conventional methods. In the past, numerous attempts have been made to predict the impact of fretting fatigue. A critical plane approach to multiaxial gatigue damage including out-of-phase loading.

Iterative fretting wear model An iterative model to predict the fatigue strength of a component subjected to fretting wear has first been developed by Paysan Load application using a pneumatic cylinder in the center of the axle Fig.

The crack will then continue growing in a direction perpendicular to the contact zone surface. Fatigue of railway axles: A cross force is applied to the end of the lever. In order to assess the fatigue strength of rotor shafts and the emergence of fretting wear, two test benches have been designed.