Contact Fatigue of Rough Elastic Surfaces in Two-Dimensional Formulation

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Ilya I. Kudish
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Rough Surfaces ◽  
Contact Region ◽  
Analytical Formula ◽  
Contact Fatigue ◽  
Near Surface ◽  
Stochastic Parameters ◽  
Mean Size ◽  
Elastic Surfaces

Solution of a contact problem for a rough elastic half-plane is considered. Surface roughness is assumed to be small and stochastic. A perturbation solution of the problem for relatively small roughness with singly connected contact region is proposed and is conveniently expressed in terms of Chebyshev polynomials. Mean distribution of pressure and mean size of the contact are obtained analytically. A pitting model for rough surfaces is considered based on a generalization of an earlier proposed contact model with some stochastic parameters. An analytical formula relating subsurface originated fatigue is considered and fatigue life of rough and smooth surfaces is obtained which shows that fatigue life of rough solids is slightly shorter than of the smooth ones. In the general case of a contact region of rough surfaces with multiple connectivity subsurface originated fatigue possesses properties similar to the case of singly connected contact region. Surface roughness may have a significant effect only on surface and near surface originated fatigue such as wear, micropitting, and shallow flaking.

Effect of Sliding Friction on Contact Stresses for Multi-Layered Elastic Bodies With Rough Surfaces

1997 ◽  
Vol 119 (3) ◽  
pp. 476-480 ◽  
Author(s):  
K. Mao ◽  
T. Bell ◽  
Y. Sun
Keyword(s):  
Sliding Friction ◽  
Rough Surfaces ◽  
Numerical Technique ◽  
Contact Region ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Near Surface ◽  
Elastic Bodies ◽  
Contact Fatigue Life

The stress distributions associated with frictionless and smooth surfaces in contact are rarely experienced in practice. Factors such as layers, friction, surface roughness, lubricant films, and third body particulate are known to influence the state of stress and the resulting rolling contact fatigue life. A numerical technique for evaluating the subsurface stresses arising from the two-dimensional sliding contact of two elastic bodies with real rough surfaces has been developed, where an elastic body contacts with a multi-layer surface under both normal and tangential forces. The presence of friction and asperities within the contact region causes a large, highly stress region exposed to the surface. The significance of these near-surface stresses is related to modes of surface distress leading to surface eventual failure (Mao et al., 1997).

Effect of Three-Dimensional Random Surface Roughness on Fatigue Life of a Lubricated Contact

1998 ◽  
Vol 120 (2) ◽  
pp. 159-164 ◽  
Author(s):  
Xiaolan Ai
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Effective Stress ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
Random Surface ◽  
Near Surface ◽  
Contact Fatigue Life ◽  
Finishing Processes ◽  
Stress Variations

A means of evaluating the surface roughness effect on contact fatigue life has been proposed. To account for stress variations caused by random surface roughness, an effective stress concept based on damage accumulation theory was employed. A point EHL analysis along with a comprehensive interior stress analysis has been performed to obtain the effective stress field under lubricated conditions. Numerical simulations were performed for surfaces produced by different finishing processes. Results show that surface roughness can cause significant stress variations in the near-surface. As a result, the effective stress at the near-surface is increased. The increased effective stress is responsible for the life reduction of the contact. Life reduction factors for contact surfaces with different finishing processes were compared.

scholarly journals Rolling Contact Fatigue Life of Case−Hardened Steel Treated by Shot Peenings with Shot Diameters of 0.05 mm and 0.30 mm

2011 ◽  
Vol 86 ◽  
pp. 645-648 ◽  
Author(s):  
Lei Wang ◽  
Guang Liang Liu ◽  
Masanori Seki ◽  
Masahiro Fujii ◽  
Qian Li
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Shot Peening ◽  
Fine Particle ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Surface Hardness ◽  
Hardened Steel ◽  
Rolling Contact ◽  
Contact Fatigue Life

In order to investigate the influence of different shot peenings on the rolling contact fatigue life of case−hardened steel, the thrust type rolling contact fatigue test was performed with a ball−on−disk contact tester. In this study, the case−hardened steel disks were treated by the fine particle peening with a shot diameter of 0.05 mm and the normal shot peening with a shot diameter of 0.30 mm. The surface hardness and the surface compressive residual stress of the test disks were increased by these peenings. On the other hand, the surface roughness of the test disks was increased by the normal shot peening, and was decreased by the fine particle peening. The rolling contact fatigue test showed that the rolling contact fatigue life of the test disks was improved by the fine particle peening, and was not improved by the normal shot peening. The rolling contact fatigue life of the test disks became longer as their surface roughness became smaller. Therefore, it follows from this that the fine particle peening, which can provide the increase in surface hardness and the decrease in surface roughness, is good for the increase in the rolling contact fatigue life of case−hardened steel.

A Parametric Investigation of Surface Initiated Rolling Contact Fatigue Using the Asperity Point Load Mechanism

2013 ◽  
Vol 577-578 ◽  
pp. 45-48
Author(s):  
Dave Hannes ◽  
B. Alfredsson
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Surface Stress ◽  
Crack Path ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Local Stress ◽  
Point Load ◽  
Rolling Contact ◽  
Residual Surface Stress

Rolling contact fatigue (RCF) will eventually become an issue for machine elementsthat are repeatedly over-rolled with high contact loads and small relative sliding motion. Thedamage consists of cracks and craters in the contact surfaces. Asperities on the contact surfacesact as local stress raisers and provide tensile surface stresses which can explain both initiationand propagation of surface initiated RCF damage. A parametric study was performed to inves-tigate the contribution of surface roughness, friction and a residual surface stress to the RCFdamage process. The effects on initiation, crack path and fatigue life at both early and devel-oped damage were examined for a gear application. Both a one-parameter-at-a-time approachand a 2-level full factorial design were carried out. Surface roughness and local friction prop-erties were found to control crack initiation, whereas the simulated crack path was primarilyaffected by the residual surface stress, especially for developed damage. Reduced surface rough-ness, improved lubrication and a compressive residual surface stress all contributed to increasethe simulated fatigue life. The asperity point load model could predict effects on RCF that areobserved with experiments. The results further support the asperity point load mechanism asthe source behind surface initiated RCF.

Effect of Roughness and Sliding Friction on Contact Stresses

1991 ◽  
Vol 113 (4) ◽  
pp. 729-738 ◽  
Author(s):  
D. M. Bailey ◽  
R. S. Sayles
Keyword(s):  
Sliding Friction ◽  
Numerical Technique ◽  
Contact Region ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Shear Stresses ◽  
Near Surface ◽  
Contact Fatigue Life ◽  
Surface Distress

The stress distributions associated with smooth surfaces in contact are rarely experienced in practice. Factors such as surface roughness, lubricant films, and third body particulates are known to influence the state of stress and the resulting rolling contact fatigue life. This paper describes a numerical technique for evaluating the complete subsurface field of stress resulting from the elastic contact of nonconforming rough bodies, based on measurements of their profile. The effect of sliding friction is included. The presence of asperities within the contact region gives rise to high shear stresses near the surface. Realistic coefficients of friction for lubricated sliding contacts (i.e., μ ≈ 0.1) causes the “smooth body” shear stresses to interact with the asperity stresses to produce a large, highly stressed region exposed to the surface. The significance of these near-surface stresses is discussed in relation to modes of surface distress which lead to eventual failure of the contacting surfaces.

Fatigue Life Enhancement of Titanium Alloy by the Development of Nano/Micron Surface Layer Using Laser Peening

2019 ◽  
Vol 19 (11) ◽  
pp. 7064-7073 ◽  
Author(s):  
S. Sudhagara Rajan ◽  
S. Swaroop ◽  
Geetha Manivasagam ◽  
M. Nageswara Rao
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
High Surface ◽  
Electron Back Scatter Diffraction ◽  
Laser Peening ◽  
Near Surface ◽  
Aerospace Applications ◽  
Beta Alloy ◽  
Stress Maximum ◽  
Bulk Hardness

Ti-15V-3Cr-3Al-3Sn (Ti-15-3) is a metastable beta alloy which is considered to be a potential alternative for Ti-6Al-4V alpha+beta alloy for aerospace applications, especially for sheet products. This paper describes the work carried out to enhance the fatigue life of Ti-15-3 in an economical way by means of laser peening without coating (LPwC) using Nd:YAG laser operating at a power density of 5 GW cm-2. In order to have a sufficient bulk hardness and high compressive stresses on the surface, as-received beta solution treated (ST) Ti-15-3 was subjected to aging (520 °C/10 h/Air-cooled) and then to LPwC. Laser peening induced a notable increase in Ra (arithmetic mean roughness), which was measured using MAHR GD-120 profilometer. The Electron Back Scatter Diffraction (EBSD) analysis of the aged sample (STA) revealed a significant increase in the alpha precipitation (20 vol%), and this led to a substantial increase in the hardness (~40%) and UTS (~50%). In addition to this, peening of aged (STA+LPwC) sample resulted in a considerable increase (~12%) in near-surface microhardness and compressive residual stress (maximum stress of -195 MPa at a depth of 150 μm). This increase in compressive stress and microhardness led to an enhancement in the fatigue life of the STA+LPwC sample by 210% when compared to STA sample. In spite of high surface roughness induced by the LPwC, fractography studies revealed that crack initiation was independent of surface roughness.

Rolling Bearing Life Modifying Factors for Film Thickness, Surface Roughness, and Friction

1981 ◽  
Vol 103 (4) ◽  
pp. 509-516 ◽  
Author(s):  
T. E. Tallian
Keyword(s):  
Experimental Data ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Film Thickness ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Bearing ◽  
Rolling Contact ◽  
Practical Calculation ◽  
Modifying Factors

This paper facilitates practical calculation of rolling contact fatigue life, allowing for material, lubrication, and surface topography effects. Modifying factors for the predicted fatigue life are given for: material matrix strength; material defect severity; EHD film thickness/surface roughness ratio Λ; surface asperity slope σθ and boundary lubricated traction coefficient μa. Readily evaluated formulas are provided for the above factors. Calculated results show predicted life versus Λ with σθ and μa as parameters. Comparison with experimental data shows that the model covers most documented test results of life versus Λ. Scanty experimental data covering σθ and traction effects on life are compatible with the model predictions.

scholarly journals Simulation of the fatigue-wear coupling mechanism of an aviation gear

Friction ◽  
2020 ◽  
Author(s):  
Boyu Zhang ◽  
Huaiju Liu ◽  
Caichao Zhu ◽  
Yibo Ge
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Contact Fatigue ◽  
Tooth Profile ◽  
Wear Depth ◽  
Fatigue Wear ◽  
Elastic Plastic ◽  
Fatigue Damage Accumulation ◽  
Material Points

AbstractThe contact fatigue of aviation gears has become more prominent with greater demands for heavy-duty and high-power density gears. Meanwhile, the coexistence of tooth contact fatigue damage and tooth profile wear leads to a complicated competitive mechanism between surface-initiated failure and subsurface-initiated contact fatigue failures. To address this issue, a fatigue-wear coupling model of an aviation gear pair was developed based on the elastic-plastic finite element method. The tooth profile surface roughness was considered, and its evolution during repeated meshing was simulated using the Archard wear formula. The fatigue damage accumulation of material points on and underneath the contact surface was captured using the Brown-Miller-Morrow multiaxial fatigue criterion. The elastic-plastic constitutive behavior of damaged material points was updated by incorporating the damage variable. Variations in the wear depth and fatigue damage around the pitch point are described, and the effect of surface roughness on the fatigue life is addressed. The results reveal that whether fatigue failure occurs initially on the surface or sub-surface depends on the level of surface roughness. Mild wear on the asperity level alleviates the local stress concentration and leads to a longer surface fatigue life compared with the result without wear.

Influence of Surface Roughness Skewness on Rolling Contact Fatigue Life

1992 ◽  
Vol 35 (4) ◽  
pp. 745-750 ◽  
Author(s):  
Yoshinobu Akamatsu ◽  
Noriyuki Tsushima ◽  
Toshihide Goto ◽  
Kenji Hibi
Keyword(s):  
Surface Roughness ◽  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Contact Fatigue Life
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