Study of a Brittle Transparent Disk Under Dry RCF Conditions

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Arthur Francisco ◽  
Houssein Abbouchi ◽  
Bernard Villechaise
Keyword(s):  
Normal Load ◽  
Rolling Contact Fatigue ◽  
Tangential Force ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Tangential Load ◽  
Primary Network ◽  
Disk Material ◽  
Number Of Cycles ◽  
The One

Despite the numerous experimental works on rolling contact fatigue, dealing with two-disk contacts, some phenomena still remain badly understood. Most of the test benches, used for that purpose, impose the rotational speeds to the disks: global slipping occurs and the tangential force is measured. Even if this configuration is found in some mechanical contacts, it does not reflect situations, where only microslipping occurs with high tangential loads. For these reasons, an original bench has been designed: a specimen disk rotates a braked stainless steel disk under a normal load N. The tangential load T, due to the braked disk, is set below the global slipping value; the specimen disks are transparent for the cracks observation and brittle to avoid any plasticity complication. A typical run consists in carrying out a succession of steps of increasing the number of cycles. Each step ends with several measurements on the cracks: their counting and their width and depth measurements. The results are divided in two categories: general observations and quantitative results. The most evident observation concerns the crack shape since it propagates along an ellipse on the contact path. Furthermore, the direction of propagation inside the disk is perpendicular to the surface. Lastly, a regular primary network of well-defined cracks is observed with cracks less marked. Concerning the effects of varying loads, the higher the T, the faster the cracks initiate and propagate because of a higher tensile stress state. However, these effects can be partly overridden by N beneath the contact path. As the disk material is brittle, the crack behavior is quite similar to the one observed on metallic specimens. Even if the results are obtained in an epoxy resin, a reasonable transposition is possible. The disk transparency makes it possible to quantify the cracks growth and to propose original 3D photographs of the cracks.

Observation of Fatigue Fracture on PEEK Shaft against Alumina Bearing’s Ball under One-Point Rolling Contact

2016 ◽  
Vol 878 ◽  
pp. 137-141 ◽  
Author(s):  
Hitonobu Koike ◽  
Genya Yamaguchi ◽  
Koshiro Mizobe ◽  
Yuji Kashima ◽  
Katsuyuki Kida
Keyword(s):  
Fatigue Fracture ◽  
Rolling Contact Fatigue ◽  
Rolling Direction ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Subsurface Crack ◽  
Mechanical Elements ◽  
The One ◽  
Alumina Ball

Tribological fatigue failure of the machined PEEK shaft was investigated through the one-point type rolling contact fatigue test between a PEEK shaft and an alumina ball, in order to explore fatigue fracture mechanism of frictional parts working at high frequency in various mechanical elements. Due to Hertzian contact of cyclic compressive stress, the subsurface crack occurred within approximately 300 μm depth from thesurface and propagated along the rolling direction. After that, the subsurface crack propagation direction changed toward the surface. The flaking occurred on the raceway of the PEEK shaft when the subsurface crack reached to the PEEK shaft surface.

Influence on Tribological Behavior of PEEK Composite Film Layer on PEEK-PTFE Bearings with Artificial Defect in Dry Condition

2021 ◽  
Vol 904 ◽  
pp. 243-249
Author(s):  
Hitonobu Koike ◽  
Koshiro Mizobe ◽  
Katsuyuki Kida
Keyword(s):  
Composite Film ◽  
Tribological Behavior ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Artificial Defect ◽  
Peek Composite ◽  
Film Layer ◽  
Number Of Cycles

In order to explore influence on tribological behavior of PEEK composite film layer in PEEK-PTFE composite radial alumina ball bearings, rolling contact fatigue tests were performed by using the PEEK bearing’s inner rings with the artificial defects in dry condition. When rotation speed and applied load were 600 rpm and 98 N, the number of cycles of the PEEK-PTFE bearings reached 1.0×107 fatigue cycles. The artificial defects with 0.02 mm depth on the raceway surface of the PEEK inner ring was covered with PEEK composite film accumulation.

A New Methodology to Evaluate the Rolling Contact Fatigue Performances of Bearing Steels With Surface Dents: Application to 32CrMoV13 (Nitrided) and M50 Steels

2003 ◽  
Author(s):  
D. Ne´lias ◽  
C. Jacq ◽  
G. Lormand ◽  
G. Dudragne ◽  
A. Vincent
Keyword(s):  
Test Specimen ◽  
Normal Load ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Experimental Procedure ◽  
Bearing Steels ◽  
Indentation Process ◽  
Hoop Stresses

A new methodology is proposed to evaluate the rolling contact fatigue (RCF) performances of bearing steels in presence of surface dents. The experimental procedure consists in denting the raceway of the test specimen with a hardness machine using spherical diamond tips of different radius, i.e. 200, 400 and 600 μm, and normal loads ranging from 5 to 50 daN. Analysis of various dent geometries yields to an analytical law with five parameters useful to fit experimental profiles for contact simulation. Besides local residual stresses and plastic strains around the dent have been obtained by finite element simulations of the indentation process. RCF tests performed on a two-disk machine have shown better performances of nitrided 32CrMoV13 steel compared to M50 reference steel. The dominating role of sliding has been highlighted and two areas where damage initiates were identified, while the effects of the normal load and hoop stresses are less marked.

Influence of Track Properties on Railway Vehicles Wheel Rolling Contact Fatigue

2008 ◽  
Author(s):  
Mahdi Mehrgou ◽  
Asghar Nasr
Keyword(s):  
Rolling Contact Fatigue ◽  
Tangential Force ◽  
Contact Fatigue ◽  
Contact Forces ◽  
Rolling Contact ◽  
Vehicle Dynamic ◽  
Wheel Load ◽  
Wheel Rolling ◽  
Railway Passenger ◽  
Vehicle Dynamic Simulation

Track properties such as rail inclination, cant and gage width have significant effects on the shape and size of the contact area, actual rolling radius and also on the contact forces. These effects have an important role on rolling contact fatigue (RCF) which is known to be the main reason for large portion of wheel set failures and expenses. In this study the wheel/rail dynamic interaction of an Iranian railway passenger wagon under different track features are investigated through simulations using ADAMS\Rail commercial software. The calculated results regarding contact load data and contact properties of the wheel and rail are used for fatigue analysis to calculate RCF damage to the wheels using damage criteria based on previous studies. Two major parameters believed to have serious roles on RCF are the contact stress and the tangential force in the contact patch. These parameters are obtained from vehicle dynamic simulation studies. This paper describes and compares effects of different track geometries in curved and tangent tracks on RCF of three different wheel profiles S1002, P8 and IR1002. It is to identify which combinations of wheel load, wheel and rail profiles and vehicle dynamic characteristics cause RCF more severely.

New Methodology to Evaluate the Rolling Contact Fatigue Performance of Bearing Steels With Surface Dents: Application to 32CrMoV13 (Nitrided) and M50 Steels

2005 ◽  
Vol 127 (3) ◽  
pp. 611-622 ◽  
Author(s):  
D. Nélias ◽  
C. Jacq ◽  
G. Lormand ◽  
G. Dudragne ◽  
A. Vincent
Keyword(s):  
Normal Load ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Rolling Contact ◽  
Experimental Result ◽  
Damage Initiation ◽  
Bearing Steels ◽  
Improved Performance

A new methodology is proposed to evaluate the rolling contact fatigue (RCF) performance of bearing steels in presence of surface dents. The experimental procedure consists of denting the raceway of test specimens with a hardness machine using spherical diamond tips of different radii (i.e., 200, 400, and 600μm) and with an applied normal load ranging from 5to50daN. Analysis of various dent geometries yield an analytical law with five parameters useful for fitting experimental profiles for contact simulation. Fatigue tests are conducted using a two-disk machine to study the effect of different operating conditions on RCF and to compare the performances of nitrided 32CrMoV13 steel versus M50 reference steel. A numerical investigation is conducted to analyze experimental result. Initially, the local residual stresses and plastic strains around the dent are obtained through finite element simulations of the indentation process. Second, the overrolling of the dent is simulated with a contact code. Finally, an indent-based endurance limit, called H1I, is proposed and comparisons are made with test results. Both RCF tests and numerical simulations show improved performance with nitrided 32CrMoV13 steel when compared to the M50 reference steel. The dominating role of sliding is also experimentally highlighted and two areas of damage initiation are identified. The effects of normal load and hoop stress are less marked.

On Ratchetting-Based Models of Wear and Rolling Contact Fatigue (RCF)

2003 ◽  
Author(s):  
M. Ciavarella ◽  
L. Afferrante
Keyword(s):  
Shear Stress ◽  
Plastic Material ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Longitudinal Direction ◽  
Surface Flow ◽  
Rolling Contact ◽  
Stress Cycle ◽  
Shakedown Theory ◽  
Number Of Cycles

Recent efforts to develop simple unified models of both wear and RCF (Kapoor & Franklin, 2000, Franklin et al., 2001) are discussed, in view of previous theoretical and experimental results on ratchetting in rolling contact. At sufficiently high contact pressures, surfaces deform plastically with unidirectional cumulation of “ratchetting” strains (Johnson, 1985, Ch.9). However, the modelling of ratchetting strains as a function of plastic material properties has turned out more complicated than what originally suggested by the first attempts (Merwin & Johnson, 1963), as recently discussed by Ponter et al. (2003). Wear due to surface ratchetting occurs for sufficiently high friction, whereas RCF is mainly due to ratchetting subsurface. It appears that experimental data on ratchetting strains in the literature unfortunately do not show a clear and unique trend, and various proposed fitting equations differ significantly in quantitative and qualitative terms, particularly at large number of cycles. It is shown that ratchetting in rolling contact is a combination of “structural ratchetting” (that modelled with the perfect plasticity model) and “material ratchetting”, and the latter is very sensitive to the hardening behaviour of the material. Also, the surface and subsurface flow regimes are very different: in pure rolling, a simplified model of the stress cycle condition is a fully reversed cycle of shear superposed to an out-of-phase pulsating compression in a extended region below the surface (neglecting other two components also of pulsating compression); increasing the friction coefficient, a mean shear stress is induced as well as a tensile component in the direct stress, and for friction f > 0.3 the maximum moves at the surface, but the highly stressed zone becomes a thin surface layer which suffers uniquely of “material ratchetting”. In the limit of very high friction, we have the critical condition on the surface which obviously gives a pulsating shear stress cycle in phase with a pulsating compression, but in addition we have a nearly fully reversed cycle of tension-compression (although the tensile peak is very localized also in the longitudinal direction). Such multiaxial stress fields and their largely different features introduced cause a response of the material which has not been studied enough, perhaps both in terms of ratchetting rates and in terms of the failure condition. In particular, the ductility for ratchetting surface flow as used in wear models seems apparently much higher than that for RCF ratchetting models. Also, RCF at large number of cycles in the C&S experiments (Clayton & Su, 1996, Su & Clayton, 1997) seems not well correlated with shakedown theory, and accordingly, simple ratchetting equations based on excess of shakedown such as that of Tyfoor et al (1996), do not seem well suited a Wohler SN life curve. However, these conclusions are only very qualitative as the materials in the two tests are different, and at present empirical separate models for wear and RCF based on hardness of materials and a posteriori data fitting seem the only quantitative way forward for engineering purposes.

Approaches to modeling occurrence of rolling contact fatigue damages in rails

2018 ◽  
Vol 77 (5) ◽  
pp. 259-268 ◽  
Author(s):  
S. M. Zakharov ◽  
E. V. Torskaya
Keyword(s):  
Laboratory Tests ◽  
Rolling Contact Fatigue ◽  
Tangential Force ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Joint Zone ◽  
The Road ◽  
Heavy Haul ◽  
Vehicle Movement ◽  
Relative Slippage

Rolling contact-fatigue damages of rails along with their wear are the most common types of rail defects. In recent years, there have been significant changes in the distribution of rolling contact fatigue damages of rails especially on railways operating under heavy haul conditions.This paper is devoted to the overview of approaches to modeling of the occurrence of rolling contact fatigue (RCF) damages on working surfaces of rails. Four types of such approaches to modeling are considered. The first is based on the methods of contact mechanics. To realize it, the vehicle movement on the characteristic sections of the track is modeled, the forces acting in contact are determined, the contact problem is solved, and the values of the linear criterion of contact fatigue damage are determined. The required characteristics of rolling contact fatigue of the rail material are established on the basis of laboratory tests. The second approach uses the diagram of the adaptability of rail material to cyclic loads, proposed by K. Johnson, established on the basis of laboratory tests. The third approach uses criteria that have the physical meaning of the energy released at the contact as an index of the product of the tangential force in contact and relative slippage. In the fourth approach predicting the accumulation of plastic deformation under conditions of cyclic loading is performed on the basis of a series of standard tests of rail steels, including in the welded joint zone, and finite element modeling. In addition, there is also a probabilistic model, based on the assumption that it is possible to transfer the results of the RCF damage of rails on the experimental section of the road to any other site.As the conclusion the authors formulated directions for further studies on the formation and development of surface rolling contact fatigue defects in rails.

Fatigue and Contact Fatigue Resistance of Thin Hard-Coated Components

2009 ◽  
Vol 417-418 ◽  
pp. 801-804
Author(s):  
Sergio Baragetti ◽  
Federico Tordini
Keyword(s):  
Vapor Deposition ◽  
State Of The Art ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Chemical Vapor ◽  
Rolling Contact ◽  
Damage Initiation ◽  
Number Of Cycles ◽  
Physical And Chemical ◽  
Contact Fatigue Resistance

In this paper a review of the state of the art on the study of the fatigue and the contact/rolling contact fatigue (RCF) resistance of thin hard-coated components is provided. Physical and chemical vapor deposition (PVD and CVD) methods are used to deposit such films. A fair number of references reports experimental data highlighting the improvements achieved with coating deposition on both steels and light alloys. Numerical modelling has also been devoted to shedding light on the behaviour of coated components and reliable previsional procedures have been arranged to foresee the number of cycles until fatigue damage initiation and failure.

Rail RCF and the Effects of Different Wheel Profiles

2008 ◽  
Author(s):  
Mehdi Mehrgou ◽  
Asghar Nasr
Keyword(s):  
Dynamic Simulation ◽  
Rolling Contact Fatigue ◽  
Tangential Force ◽  
Contact Fatigue ◽  
Simulation Software ◽  
Contact Forces ◽  
Rolling Contact ◽  
Dynamic Interactions ◽  
Railway Passenger ◽  
Vehicle Dynamic Simulation

Wheel lateral profile has considerable effects on the wheel/rail dynamic interactions such as the shape and size of the contact area, instantaneous rolling radius and contact forces. Theses themselves have indirectly important roles on the rolling contact fatigue (RCF) which is known to be the main reason for large portion of rail maintenance costs. In this study the wheel/rail dynamic interaction of an Iranian railway passenger wagon under three different wheel profiles are investigated using ADAMS\Rail commercial simulation software. The dynamic simulation results regarding contact load and contact features of the wheel and rail are used for fatigue analysis to calculate RCF damage to the rail using reliable damage criteria reported in the literature. The two major parameters having serious roles on the RCF are believed to be the contact stress and the tangential force at the contact patch. These parameters are obtained from vehicle dynamic simulation studies. This paper describes and compares the effects of three different wheel profiles known as S1002, P8 and IR1002 on the rail RCF in both the curved and tangent sections of a track. The primary results clearly identify the effects of wheel profile on the RCF.

scholarly journals Flaking of PEEK under one-point rolling contact fatigue using Al2O3 ball

2019 ◽  
Vol 264 ◽  
pp. 01004
Author(s):  
Hitonobu KOIKE ◽  
Genya YAMAGUCHI ◽  
Koshiro MIZOBE ◽  
Katsuyuki KIDA
Keyword(s):  
Fatigue Cracks ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Surface Cracks ◽  
Subsurface Crack ◽  
Near Surface ◽  
The One ◽  
Point Type

The growth of flaking as tribological fatigue failure in PEEK was investigated through the one-point type rolling contact fatigue test between a machined PEEK polymer shaft and an alumina bearing's ball. Due to Hertzian contact of cyclic compressive stress, the subsurface fatigue cracks in the PEEK shaft propagated in rolling and axial directions. When the rolling fatigue life of the PEEK shaft reached 106 fatigue cycles, many narrow angled cracks occurred in the near-surface of the rolling track without flaking. On the other hand, when the flaking ocuurred on the PEEK shaft before 106 fatigue cycles, semicircular surface and subsurface crack propagations were observed. From these observations, it was found that micro-flaking occurred due to the linkages between subsurface and surface cracks. Flakingdeveloped due to the accumulation of these micro-flakings.

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