According to Carter et al. This critical plane is found by calculating a value from a distinct combination of stresses and strains, systematically for varying plane orientations. Since wear marks can already be witnessed on the rotor shafts of today’s turbine assemblies, an examination of both the fatigue behavior and the emergence of fretting is necessary. Signs of fretting at the bearing seat of rotor shafts from different manufacturers At the same time a more light-weight design of the rotor shaft is desired. A stress-strain function for the fatigue of metals. Guclu, Railway axle analyses:
Position of strain gauges during the static test was detected before this was achieved. Further developments have been made by Ding et al. Figure 2 shows the testing machine and the axles used for the fatigue tests . When a surface crack is induced by fretting in a region of high cyclic strain, a growing crack can lead to a complete failure of the component. This way the prediction accuracy of the fretting fatigue estimation models can be determined.
According to Maiwaldbearings that are subjected to large bending moments and axial loads will experience not only an axial slip between jn and inner ring of the main bearing, but also a tangential creeping movement of the inner ring on the shaft. Results obtained from analytical analysis could help to make a damagetolerant design, and to optimize the safety and planning of maintenance .
By the means ij 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.
Fatigue tests can be performed using test machines in which the axle rotates or zxles frequently on Sincotec resonance test machines . 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.
Information related to the author. The rotating bending moment from aerodynamic loads green line is, due to the random characteristics of the distribution of the wind speed, less predictable.
Analysis of Transverse Cracks Forming in a Railway Axle
The decomposition levels were analyzed from 5 to 9. Hirakawa, Fundanmental investigations of fretting fatigue Part 5.
According to Herrmann et al. In rolling stock one of the components vulnerable to damage is the axle.
Multiaxial models try to take into consideration the time-variant and non-proportional nature of contact stresses. 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.
Effect of Understress on Fretting Fatigue Crack Initiation of Press-Fitted Axle
Q He, B Liu, X. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. A cross force is applied to the end of the lever. One setup is in full scale, the other one in 1: Cumulative frequency distribution of nominal bending stresses at the bearing seat frerting the rotor shaft blue and green line are presented qualitatively.
At the small test bench the bending moment is applied by two cross forces blue hydraulic cylinders. The rotor shaft of a wind turbine and thesia typical loads are clarified. Crack initiation criteria in fretting fatigue.
New stopping criteria for crack detection during fatigue tests of railway axles
Randall, Detection and diagnosis of incipient bearing failurein helicopter gearboxes, Engineering Failure Analysis 11 2 — Journal of Materials Engineering. As a service to our customers we are providing this early version of the manuscript. In addition, a torsional moment, an axial force and cross forces are induced. Railay the test, the surfaces of the shafts under the main bearing will be investigated in detail.
Dissimilar to Continuous Wavelet Transform, Discrete Wavelet Transform DWT is more commonly used because the computational cost is lower and the signals usually comprise discrete data.
New stopping criteria for crack detection during fatigue tests of railway axles – PDF Free Download
This specific rotor shaft completely failed after only hours 22 months of turbine operation. In total, six shafts made from forged steel 42CrMo4 will be tested at different load levels. Byeong Choon Goo, C.
The condition of the axle was then checked using UT and MT. The crack will then continue growing in a direction perpendicular to the contact zone surface.
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