The Effect of Dent Size on the Pressure Distribution and Failure Location in Dry Point Frictionless Rolling Contacts

2004 ◽  
Vol 126 (3) ◽  
pp. 413-421 ◽  
Author(s):  
M. B. Howell ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Pressure Distribution ◽  
Point Contact ◽  
Strain Range ◽  
Material Model ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Element Simulation ◽  
Rolling Contacts ◽  
Failure Location ◽  
Versus Strain

Finite element simulation is performed for rolling contact over four different size spherical dents. Two rolling contacts are simulated using a portion of a sphere as a counter-face to the dented half-space. The effect of dent size on the pressure distribution and fatigue failure location for dry point contact is studied. The material model used was adjusted to match both the stress amplitude versus strain range curve and ratchetting experimental data for 52100 bearing steel.

Numerical Simulation on Rolling Contact Fatigue with Dent at Rolling Surface

2007 ◽  
Vol 353-358 ◽  
pp. 1094-1097 ◽  
Author(s):  
Fan Fei Zeng ◽  
Li Sha Niu ◽  
Hui Ji Shi
Keyword(s):  
Fatigue Failure ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Rolling Surface ◽  
Element Simulation ◽  
Critical Plane Approach ◽  
Calculation Results ◽  
Failure Location ◽  
Good Agreement

This work has investigated the effect of spherical dent on rolling contact fatigue (RCF). A 3-D finite element simulation model of bearing rolling contact incorporating critical plane approach has been developed to study the fatigue failure location. It was found that the fatigue failure locations were significantly influenced by the dent. The calculation results are in good agreement with the experimental results and comparable with the results from the published literatures in which 2-D models were generally used.

Traction of Lubricated Rolling Contacts Between Thin Film Coatings and Steel

2007 ◽  
Author(s):  
Ryan D. Evans ◽  
J. David Cogdell ◽  
Gary L. Doll
Keyword(s):  
Thin Film ◽  
Rolling Contact ◽  
Carbon Coatings ◽  
Test Configuration ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Rolling Contacts ◽  
Traction Coefficient ◽  
Coated Surfaces ◽  
Stribeck Curves

Tribological thin film coatings can enhance performance in mechanical components such as bearings and gears. Although lubricant is present in most applications, the interactions of the lubricant with coated surfaces are not always well understood. In the present study, Stribeck curves (i.e., traction coefficient vs. dimensionless film thickness Λ) were generated for lubricated rolling contact between coated and uncoated surfaces. Chromium nitride, tungsten carbide reinforced amorphous hydrocarbon, and silicon-incorporated diamond-like carbon coatings are evaluated. A ball-on-flat test configuration is used in a 100% slide-to-roll condition. The test lubricant was a polyalphaolefin containing rust and oxidation inhibitor additives only. Differences in traction performance are observed for different coating types. The traction coefficient decreases at high Λ with increasing hydrocarbon content in the coating. The combination of coating micro-texture and composition are believed to influence traction as A becomes small.

scholarly journals Lubrication Analyses of Cam and Flat-Faced Follower

Lubricants ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 31 ◽  
Author(s):  
Hazim U. Jamali ◽  
Amjad Al-Hamood ◽  
Oday I. Abdullah ◽  
Adolfo Senatore ◽  
Josef Schlattmann
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Surface Deformation ◽  
Numerical Study ◽  
Point Contact ◽  
Radius Of Curvature ◽  
Operating Cycle ◽  
Essential Step ◽  
Parabolic Shape ◽  
Principal Factors

The principal factors that affect the characteristics of contact problem between cam and follower vary enormously during the operating cycle of this mechanism. This includes radius of curvature, surface velocities and applied load. It has been found over the last decades that the mechanism operates under an extremely thin film of lubricant. Any practical improvement in the level of film thickness that separates the contacted surfaces represents an essential step towards a satisfactory design of the system. In this paper a detailed numerical study is presented for the cam and follower (flat-faced) lubrication including the effect of introducing an axial modification (parabolic shape) of the cam depth on the levels of film thickness and pressure distribution. This is achieved based on a point contact model for a cam and flat-faced follower system. The results reveal that the cam form of modification has considerable consequences on the level of predicted film thickness and pressure distribution as well as surface deformation.

Effect of Repeated Quenching on the Rotating Bending Strength of SAE52100 Bearing Steel

2012 ◽  
Vol 457-458 ◽  
pp. 1025-1031 ◽  
Author(s):  
Koshiro Mizobe ◽  
Edson Costa Santos ◽  
Takashi Honda ◽  
Hitonobu Koike ◽  
Katsuyuki Kida ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Bending Strength ◽  
High Strength ◽  
Bearing Steel ◽  
Rolling Contact ◽  
High Wear Resistance ◽  
High Carbon ◽  
Austenite Grain ◽  
High Fatigue ◽  
Rotating Bending

Martensitic high carbon high strength SAE 52100 bearing steel is one of the main alloys used for rolling contact applications where high wear resistance are required. Due to its high fatigue strength, SAE 52100 is recently being used not only for the production of bearings but also shafts. Refining of prior austenite grain through repeated quenching is a procedure that can be used to enhance the material’s strength. In this work, the microstructure of repeatedly quenched SAE 52100 steel and its fatigue strength under rotating bending were investigated. It was found that repeated furnace heating and quenching effectively refined the martensitic structure and increased the retained austenite content. Repeated quenching was found to improve the fatigue strength of SAE 52100.

Virtual Material Model of Joint Interfaces Considering Elastic-Plastic Deformation of Asperities

2013 ◽  
Vol 457-458 ◽  
pp. 257-261
Author(s):  
Li Gang Cai ◽  
Teng Yun Xu ◽  
Yong Sheng Zhao
Keyword(s):  
Plastic Deformation ◽  
Elastic Modulus ◽  
Fractal Theory ◽  
Material Model ◽  
Contact Theory ◽  
Hertz Contact ◽  
Calculation Methods ◽  
Elastic Plastic ◽  
Element Simulation ◽  
Simulation Results

A virtual material model of joint interfaces was established based on the Hertz contact theory and fractal theory, this model was improved by considering the influence of the elastic-plastic deformation of asperities and ameliorating the calculation methods of the elastic modulus. The simulation results of elastic-plastic considered and elastic-plastic unconsidered were compared, moreover, the finite element simulation results and experimental results were compared to fully explain the necessity of considering the influence of the elastic-plastic deformation and the the correctness of the method to calculate the elastic modulus. The research suggested that under a same load the elastic modulus of the model considering the influence of the elastic-plastic deformation was slightly larger than the un considering one, which means it could describe the characteristics of joint interfaces more accurately.

A New Approach for Fatigue Damage Modeling of Subsurface-Initiated Spalling in Large Rolling Contacts

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Aditya A. Walvekar ◽  
Neil Paulson ◽  
Farshid Sadeghi ◽  
Nick Weinzapfel ◽  
Martin Correns ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Damage Mechanics ◽  
Numerical Models ◽  
Rolling Contact ◽  
Fe Model ◽  
Triangle Mesh ◽  
Computationally Efficient ◽  
New Approach ◽  
Rolling Contacts ◽  
Delaunay Triangle

Large bearings employed in wind turbine applications have half-contact widths that are usually greater than 1 mm. Previous numerical models developed to investigate rolling contact fatigue (RCF) require significant computational effort to study large rolling contacts. This work presents a new computationally efficient approach to investigate RCF life scatter and spall formation in large bearings. The modeling approach incorporates damage mechanics constitutive relations in the finite element (FE) model to capture fatigue damage. It utilizes Voronoi tessellation to account for variability occurring due to the randomness in the material microstructure. However, to make the model computationally efficient, a Delaunay triangle mesh was used in the FE model to compute stresses during a rolling contact pass. The stresses were then mapped onto the Voronoi domain to evaluate the fatigue damage that leads to the formation of surface spall. The Delaunay triangle mesh was dynamically refined around the damaged elements to capture the stress concentration accurately. The new approach was validated against previous numerical model for small rolling contacts. The scatter in the RCF lives and the progression of fatigue spalling for large bearings obtained from the model show good agreement with experimental results available in the open literature. The ratio of L10 lives for different sized bearings computed from the model correlates well with the formula derived from the basic life rating for radial roller bearing as per ISO 281. The model was then extended to study the effect of initial internal voids on RCF life. It was found that for the same initial void density, the L10 life decreases with the increase in the bearing size.

Optimized Mapping of Pressure in Lubricated Point Contacts Based on Measured Film Thickness

2007 ◽  
Author(s):  
Radek Polisˇcˇuk ◽  
Michal Vaverka ◽  
Martin Vrbka ◽  
Ivan Krˇupka ◽  
Martin Hartl
Keyword(s):  
Film Thickness ◽  
Numerical Solution ◽  
Point Contact ◽  
Contact Fatigue ◽  
Lubricant Film ◽  
Rolling Contact ◽  
Experimental Film ◽  
Lubricated Contacts ◽  
Practical Performance ◽  
Traction Drives

The surface topography plays significant role in lifetime of highly loaded machine parts with lubricated contacts. Many elements like gears, rolling bearings, cams and traction drives operate in mixed lubrication conditions, where the lubricant film behavior closely implies the main practical performance parameters such as friction wear, contact fatigue and scuffing. For prediction of wear and especially contact fatigue, the values and distribution of the pressure in rolling contact are often required. The usual theoretical approach based on numerical solution of physical-mathematical models built around the Reynolds equation can be extremely time consuming, especially when lubricant films are very thin, and contact load and required resolution very high. This study presents a further refined approach to our previously published experimental method, based on on inverse elasticity theory and fast convolution transformation between the lubricant film thickness map and the pressure distribution within the point contact. The experimental film thickness maps of EHD lubricated contacts with smooth and dented surfaces were processed using colorimetric interferometry and validated using numerical solution, in order to calibrate numerical parameters and to find limits of the new approach.

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