Closure to “Discussions of ‘A New Fatigue Life Model for Rolling Bearings’” (1985, ASME J. Tribol., 107, pp. 377–378)

1985 ◽  
Vol 107 (3) ◽  
pp. 378-378 ◽  
Author(s):  
E. Ioannides ◽  
T. A. Harris
Keyword(s):  
Fatigue Life ◽  
Rolling Bearings ◽  
Life Model

A New Fatigue Life Model for Rolling Bearings

1985 ◽  
Vol 107 (3) ◽  
pp. 367-377 ◽  
Author(s):  
E. Ioannides ◽  
T. A. Harris
Keyword(s):  
Fatigue Life ◽  
Rolling Bearing ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Rolling Bearings ◽  
Structural Fatigue ◽  
Probability Of Survival ◽  
Life Model ◽  
Life Predictions ◽  
Fatigue Criterion

This paper describes a novel model for the prediction of fatigue life in rolling bearings. Central to this model is the postulation of a statistical relationship between the probability of survival, the fatigue life, and a stress-related fatigue criterion level above a fatigue limit for an elementary volume of material in the bearing. Using this concept, the stress volume to fatigue and the fatigue life of the bearing can be calculated for different loads, material and operating conditions. Comparisons between experimentally obtained rolling bearing fatigue lives and lives predicted using this theory indicate its ability to account for phenomena hitherto excluded from fatigue life predictions. Furthermore, comparisons between experimentally obtained fatigue lives for other specimens used in structural fatigue tests and fatigue lives predicted using the new model show good agreement.

Fatigue Life Investigation of Solid and Hollow Rollers in Pure Rolling Contact

2005 ◽  
Author(s):  
W. Abu Jadayil ◽  
D. Flugrad ◽  
A. Qamhiyah
Keyword(s):  
Fatigue Life ◽  
Contact Zone ◽  
Peak Stress ◽  
Rolling Contact ◽  
Solid Cylinder ◽  
Rolling Bearings ◽  
Pure Rolling ◽  
Life Model ◽  
Finite Element Package ◽  
Hollow Cylinders

Two solid and hollow cylindrical rollers in pure rolling contact have been modeled. The two rollers are subjected to a combined normal and tangential loading. The Stress distribution in the contact zone has been determined using a finite element package called ABAQUS. Then fatigue life model for rolling bearings developed by Ioannides and Harris has been used to study the relative fatigue life of the hollow rollers compared to solid rollers. Different hollowness percentages have been investigated; 20%, 40%, 60% and 80%. Two cases were studied- when both rollers are hollow and when only one of them is hollow while the other one is solid. It has been found that making the rollers hollow will result in redistribution of stresses in the contact zone. That decreased the peak stress under the surface when compared to the solid cylinder. Hollow cylinders have more flexibility when subjected to normal and tangential loading. And so, the stresses are redistributed so that the fatigue life is improved. The best fatigue life improvements have been found when both cylinders have almost 60% hollowness.

The Effect of the EHD Pressure Spike on Rolling Bearing Fatigue

1987 ◽  
Vol 109 (3) ◽  
pp. 444-450 ◽  
Author(s):  
L. Houpert ◽  
E. Ioannides ◽  
J. C. Kuypers ◽  
J. Tripp
Keyword(s):  
Pressure Distribution ◽  
High Stress ◽  
Surface Damage ◽  
Rolling Bearing ◽  
Shear Stresses ◽  
Stress Concentrations ◽  
Surface Layers ◽  
Rolling Bearings ◽  
Life Model ◽  
Pressure Spike

A recently proposed fatigue life model for rolling bearings has been applied to the study of lifetime reduction under conditions conducive to microspalling. The presence of a spike in the EHD pressure distribution produces large shear stresses localized very close to the surface which may account for early failure. This paper describes a parametric study of the effect of such spikes. Accurate stress fields in the volume are calculated for simulated pressure spikes of different height, width and position relative to a Hertzian pressure distribution, as well as for different lubricant traction coefficients and film thicknesses. Despite the high stress concentrations in the surface layers, reductions in life predicted by the model are modest. Typically, the pressure spike may halve the life, with the implication that subsurface fatigue still dominates. In corroboration of this prediction, preliminary experimental work designed to reproduce microspalling conditions shows that microindents due to overrolling particles are a much more common form of surface damage than microspalling.

scholarly journals Fatigue Life Prediction of Rolling Bearings Based on Modified SWT Mean Stress Correction

2020 ◽  
Author(s):  
Aodi Yu ◽  
Hong-Zhong Huang ◽  
Yan-Feng Li ◽  
He Li ◽  
Ying Zeng
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Stress Ratio ◽  
Prediction Models ◽  
Great Influence ◽  
Sensitivity Coefficient ◽  
Model Verification ◽  
Mean Stress ◽  
Test Results ◽  
Rolling Bearings

Abstract Mean stress has a great influence on fatigue life, commonly used stress-based life prediction models can only fit the test results of fatigue life under specific stress ratio or mean stress but cannot describe the effect of stress ratio or mean stress on fatigue life. Smith, Watson and Topper (SWT) proposed a simple mean stress correction criterion. However, the SWT model regards the sensitivity coefficient of all materials to mean stress as 0.5, which will lead to inaccurate predictions for materials with a sensitivity coefficient not equal to 0.5. In this paper, considering the sensitivity of different materials to mean stresses, compensation factor is introduced to modify the SWT model, and several sets of experimental data are used for model verification. Then, the proposed model is applied to fatigue life predictions of rolling bearings, and the results of proposed method are compared with test results to verify its accuracy.

An Optimum Design of Crowned Cylindrical Roller Bearings Using Genetic Algorithms

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
K. Sunil Kumar ◽  
Rajiv Tiwari ◽  
P. V. V. N. Prasad
Keyword(s):  
Genetic Algorithms ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Stress Concentrations ◽  
Rolling Bearings ◽  
Design Constraint ◽  
Roller Bearings ◽  
Edge Stress ◽  
Heavy Loads ◽  
Cylindrical Roller

The long fatigue life is the one of the most important criterion for the design of rolling bearings, however, due to complex and diverse internal geometries, each type of rolling bearings require a different design formulation. To increase the life of cylindrical roller bearings, the profile (or the crowning) of the roller plays an important role. A flat profile of the rolling element results in the edge stress concentrations at roller ends. A circular crowning of roller eliminates the edge stress concentration at the lower and moderate loads only; however, it develops edge stress concentrations at heavy loads. The logarithmic profile of the roller results in no edge stress concentration at the low, medium, and heavy loads; distribution of contact stresses is also nearly uniform along the length of the roller. A design methodology for the optimum design of cylindrical roller bearings with the logarithmic profile has been outlined. A nonlinear constrained optimization problem has been formulated for the design of cylindrical roller bearings with logarithmic profiles and is optimized by using real-coded genetic algorithms. The change in roller profile has not been accounted for explicitly in the standard definition of the dynamic capacity; hence, for the present case directly the Lundberg–Palmgren life equation has been chosen as an objective function. Design variables include four bearing geometrical parameters and the two logarithmic profile generating parameters are considered. In addition to these, another five design constraint constants are also included, which indirectly affect the fatigue life of cylindrical roller bearings. The five design constraint constants have been given bounds based on the parametric studies through initial optimization runs. The effective length of the roller is taken corresponding to the standard roller diameter, which has standard discrete dimensions. Constraint violation study has been performed to have an assessment of the effectiveness of each of the constraints. A convergence study has been carried out to ensure the global optimum point in the design. A sensitivity analysis of various geometric design parameters has been performed using the Monte Carlo simulation technique, in order to see changes in the fatigue life of the bearing. Illustrations show that the multiplier of the logarithmic profile deviation parameter has more effect on the fatigue life as compared with other geometric parameters.

Fatigue Strength of Ribbon Bonds

2010 ◽  
Author(s):  
S. M. Bresney ◽  
A. Saigal
Keyword(s):  
Thermal Expansion ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Manufacturing Process ◽  
Electronic Components ◽  
Mechanical Method ◽  
Temperature Changes ◽  
Life Model ◽  
Short Span ◽  
Different Levels

Ribbon or wire bonding is a common manufacturing process used in the microelectronic industry to make interconnections between electronic components. This process is used because it can make up for misalignment and inconsistent spacing between the components due to tolerance stack ups. In addition, since the ribbons are not rigid they will flex and absorb any stresses that develop when the components expand and contract in the field due to temperature changes. This paper investigates the use of a mechanical method to exercise ribbons in this fashion until they failed. Ribbons of a constant profile but different sizes were exercised at different levels of stress to develop a fatigue life model. It is found that ribbons exercised only a small percentage of their overall span survive exponentially longer than the same ribbons exercised at a higher percentage of their overall span. In addition, at short span lengths relative to the thickness, the ribbon becomes less ‘thread like’ and more stiff. The model developed in this study can be used for designing ribbon size and shape based upon expected thermal expansion cycling and necessary life or reliability.

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