scholarly journals Theoretical and Experimental Study of Carbon-Carbon Composites Contact Fatigue Failure

2021 ◽  
Vol 42 (5) ◽  
pp. 539-551
Author(s):  
P.O. Bukovskiy ◽  
◽  
I.G. Goryacheva ◽  
Keyword(s):  
Experimental Study ◽  
Fatigue Failure ◽  
Contact Fatigue ◽  
Carbon Composites

scholarly journals Evaluation of contact fatigue risk of a carburized gear considering gradients of mechanical properties

Friction ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 1039-1050
Author(s):  
Wei Wang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Jinyuan Tang ◽  
Chenxu Jiang
Keyword(s):  
Mechanical Properties ◽  
Fatigue Failure ◽  
Equivalent Stress ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Engineering Practice ◽  
Case Hardening ◽  
Failure Risk ◽  
Spalling Failure ◽  
Carburized Gear

AbstractCarburized gears are widely used in geared machines such as wind turbines. Contact fatigue problems occur in engineering practice, reducing reliabilities of machines. Contact fatigue failures are related to many factors, such as gradients of mechanical properties of the hardening layer. In this work, an elastic-plastic contact model of a carburized gear is developed based on the finite element method to evaluate contact fatigue failure risk, considering variations in hardness and strength. The Dang Van multiaxial equivalent stress is calculated via Python coding within the Abaqus framework. The gradient of yield strength along the depth from case to core is considered. The concept of local material fatigue failure risk is defined to evaluate the probability of pitting failure. The effects of design factors, such as the case hardening depth (CHD), surface hardness, and contact pressure on fatigue failure risk, are studied. As the CHD increases or the surface hardness decreases, the risk of deep spalling failure reduces. The increase in surface hardness leads to a decreased risk of pitting failure, while the variation in CHD hardly affects the pitting failure risk.

A Possible Mechanism for Rail Dark Spot Defects

1998 ◽  
Vol 120 (2) ◽  
pp. 304-309 ◽  
Author(s):  
M. Kaneta ◽  
K. Matsuda ◽  
K. Murakami ◽  
H. Nishikawa
Keyword(s):  
Fracture Mechanics ◽  
Fatigue Failure ◽  
High Speed ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Traction Force ◽  
Rolling Contact ◽  
Dark Spot ◽  
A Posteriori ◽  
Direction Opposite

Rail dark spot defect, also termed squat failure or shelling, which is a kind of rolling contact fatigue failure and occurs frequently on running surfaces of railway rails carrying high speed traffic, is one of the most dangerous rail failures. The dark spot crack is characterized by a principal crack propagating in the direction of traffic and a second crack growing in the direction opposite to traffic. By using a newly developed two-disk machine, the authors have succeeded in reproducing very similar dark spot cracks to those which appear in actual rails. It is found that the dark spot defects are caused by frequent repetitions of dry and wet runnings, and that the traction force plays an important role for the occurrence of the cracks. The principal crack may occur from a tiny pit formed a posteriori on the contacting surface and after that, the second crack is formed by cracks branched from the extended principal crack. It has also been proved experimentally that water is capable of entering the tip of the crack. Furthermore, a possible mechanism for the dark spot cracking has been proposed on the basis of the fracture mechanics approach.

AN EXPERIMENTAL STUDY ON FATIGUE CHARACTERISTICS FOR VISCOELASTIC SUSPENSIONS OF CONSTRUCTION VEHICLES

2008 ◽  
Vol 32 (2) ◽  
pp. 181-194 ◽  
Author(s):  
Da-Gang Sun ◽  
Yong Song ◽  
Xue-Liang Zhang ◽  
Mu-Yi Lin
Keyword(s):  
Experimental Study ◽  
Fatigue Failure ◽  
Failure Criteria ◽  
Research Subject ◽  
Cycle Index ◽  
Failure Characteristics ◽  
Fatigue Characteristics ◽  
Experimental Values ◽  
New Research ◽  
Allowable Temperature

To acquire the fatigue characteristics of viscoelastic suspensions mounted in newly-developed construction vehicles, an experimental study of fatigue characteristics should be carried out on the vibration damping rubber suspension components. However, due to the lack of corresponding fatigue failure criteria for the damping rubber components, how to determine the parameters for the accelerated fatigue experiments becomes a new research subject. Based on the accelerated fatigue experiments on the viscoelastic suspensions, the parameters on fatigue failure characteristics such as the cycle index (ne), the slope (k) of S–N logarithm curve and the allowable temperature rise, and so on, were investigated. To develop a new viscoelastic suspension for the crawler bulldozer, three types of rubber made from different formulas for the viscoelastic suspensions were studied and their experimental loads were divided into 8 levels in terms of the practical working conditions of the bulldozer. The accelerated fatigue experiments of viscoelastic suspensions were performed and the obtained parameters were applied to the fatigue experiments for the suspensions of a newly-designed 386 kW crawler bulldozer. Under the industrial application over 4,000 hours, the results were shown to be consistent with the predicted experimental values.

Sign in / Sign up

Export Citation Format

Share Document