Lundberg-Palmgren Fatigue Theory: Considerations of Failure Stress and Stressed Volume

1999 ◽  
Vol 121 (1) ◽  
pp. 85-89 ◽  
Author(s):  
T. A. Harris ◽  
Wei Kuei Yu
Keyword(s):  
Life Prediction ◽  
Fatigue Cracking ◽  
Shear Stresses ◽  
Rolling Bearings ◽  
Surface Shear ◽  
Cross Sectional ◽  
Stressed Volume ◽  
Bearing Raceway ◽  
Distribution Of Stress ◽  
Maximum Contact

Load ratings and fatigue life prediction of rolling bearings is based on the Lundberg-Palmgren theory first published in Sweden in 1947. The basic equation of this theory includes the stressed volume of material in the bearing raceway subsurfaces as a major parameter. This volume of material is simplistically determined to have a nearly rectangular subsurface cross-sectional area bounded by the length of the maximum contact area ellipse and the depth at which the maximum failure-causing stress occurs. The latter stress is assumed to be effective over this area. In fact, a distribution of stress occurs, and in this investigation it is demonstrated that the subsurface volume with a potential for fatigue cracking is substantially different from that used by Lundberg and Palmgren. This difference in volume, particularly in the presence of surface shear stresses, can have a profound effect on the method and prediction of bearing fatigue lives.

scholarly journals A process-based method for predicting lateral erosion rates

2021 ◽  
Author(s):  
Myron van Damme
Keyword(s):  
Soil Mechanics ◽  
High Surface ◽  
Shear Stresses ◽  
Empirical Equations ◽  
Predictive Capability ◽  
Surface Shear ◽  
Erosion Rates ◽  
Material Texture ◽  
Empirical Coefficients ◽  
The Impact

AbstractAn accurate means of predicting erosion rates is essential to improve the predictive capability of breach models. During breach growth, erosion rates are often determined with empirical equations. The predictive capability of empirical equations is governed by the range for which they have been validated and the accuracy with which empirical coefficients can be established. Most empirical equations thereby do not account for the impact of material texture, moisture content, and compaction energy on the erosion rates. The method presented in this paper acknowledges the impact of these parameters by accounting for the process of dilation during erosion. The paper shows how, given high surface shear stresses, the erosion rate can be quantified by applying the principles of soil mechanics. Key is thereby to identify that stress balance situation for which the dilatency induced inflow gives a maximum averaged shear resistance. The effectiveness of the model in predicting erosion rates is indicated by means of three validation test cases. A sensitivity analysis of the method is also provided to show that the predictions lie within the range of inaccuracy of the input parameters.

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.

Assessment of sand stabilization potential of a plant-derived biomass

2016 ◽  
Vol 23 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Dunja Perić ◽  
Paul A. Bartley ◽  
Lawrence Davis ◽  
Ali Ulvi Uzer ◽  
Cahit Gürer
Keyword(s):  
Area Ratio ◽  
Cross Sectional Area ◽  
Experimental Program ◽  
Early Age ◽  
Shear Stresses ◽  
Sectional Area ◽  
Cross Sectional ◽  
Near Surface ◽  
Total Cross Sectional Area ◽  
Dry Sand

AbstractLignin is a coproduct of biofuel and paper industries, which exhibits binding qualities when mixed with water. Lignin is an ideal candidate for a sustainable stabilization of unpaved roads. To this end, an experimental program was devised and carried out to quantify effects of lignin on compaction and early age shear strength behaviors of sand. Samples were prepared by mixing a particular type of coproduct called calcium lignosulfonate (CaL) with sand and water. Based on the extensive analyses of six series of strength tests, it was found that a normalized cohesion increased with an increasing normalized areas ratio. Normalizations were carried out by dividing the cohesion and area ratio by gravimetric CaL content whereby the area ratio was obtained by dividing the portion of the cross-sectional area occupied with lignosulfonate-water (CaL-W) paste by the total cross-sectional area. While the increase in the normalized cohesion eventually leveled out, the cohesion peaked at 6% of CaL. Thus, sand-CaL-water (S-CaL-W) mixes sustained larger shear stresses than dry sand for a range of normal stresses below the limiting normal stress. Consequently, the early age behavior indicates that adding CaL-W to sand is clearly beneficial in the near-surface applications in dry sand.

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.

scholarly journals Remaining Useful Life Prediction of Rolling Bearings Using Electrostatic Monitoring Based on Two-Stage Information Fusion Stochastic Filtering

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ying Zhang ◽  
Anchen Wang
Keyword(s):  
Life Prediction ◽  
Engineering Application ◽  
Rolling Bearing ◽  
Gaussian Mixture ◽  
Remaining Useful Life ◽  
Joint Probability Distribution ◽  
Rolling Bearings ◽  
Two Stage ◽  
Stochastic Filtering ◽  
Useful Life

The accurate prediction of the remaining useful life (RUL) of rolling bearings is of great significance for a rational formulation of maintenance strategies and the reduction of maintenance costs. According to the two-stage nonlinear degradation characteristics of rolling bearing operation, this paper proposes a prognosis model based on modified stochastic filtering. First, multiple features reextracted from the time domain, frequency domain, and complexity angles, and the baseline Gaussian mixture model (GMM) is established using the normal operating data after spectral regression. The Bayesian-inferred distance (BID) is used as a quantitative indicator to reflect the bearing performance degradation degree. Then, taking multiparameter fusion results as input, the relationship between BID and remaining life is established by the two-stage stochastic filtering model to realize online dynamic remaining useful life prediction. The method in this paper overcomes the difficulty of accurately defining the failure threshold of rolling bearing. At the same time, it reduces the computational burden, avoiding the need of calculating the joint probability distribution for high-dimensional data. Finally, the proposed method has been verified experimentally to have high precision and engineering application value.

Laboratory Comparison of Permanent Deformation and Fatigue Behavior of Neat, Polymer, and Rubber-Asphalt Binders

2019 ◽  
Vol 2673 (4) ◽  
pp. 524-532
Author(s):  
Felipe F. Camargo ◽  
Kamilla Vasconcelos ◽  
Liedi L. Bernucci
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Behavior ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Fatigue Life Prediction ◽  
Polymer Modification ◽  
Neat Polymer ◽  
Percentage Recovery

Fatigue cracking and rutting are among the major types of distresses to be considered in flexible pavement design. In this context, the choice of the asphalt binder plays a major role in both the fatigue behavior and permanent deformation resistance of the asphalt mixture. This study was conducted to assess the permanent deformation and fatigue behavior of a field-blended rubber-asphalt (CRMA) and compare the results with typical binders used in Brazil. The neat binder used for modification was also employed as a control and as a base for polymer modification (SBSA). The binders were evaluated using the multiple stress creep and recovery (MSCR) for permanent deformation behavior, and the time sweep (TST) and linear amplitude sweep (LAS) tests for fatigue behavior. Modification of the neat binder resulted in an increase in percentage recovery in the MSCR, whereas the percentage recovery for CRMA was the highest among the three binders at any given temperature. The non-recoverable creep compliance for the CRMA was lower than that exhibited by the neat and SBSA binders for both stress levels for the range of temperatures tested. Binder modification resulted in an improved fatigue behavior compared with the neat binder according to the TST and LAS, whereas rubber modification resulted in the best fatigue behavior. Fatigue life prediction by TST was consistently higher than fatigue life prediction in the LAS test, probably because different criteria were used for determining failure in each test (ranking of the binders remained constant regardless of the criteria used).

Antiplane Shear Deformations for Homogeneous and Inhomogeneous Anisotropic Linearly Elastic Solids

1994 ◽  
Vol 61 (1) ◽  
pp. 23-29 ◽  
Author(s):  
C. O. Horgan ◽  
K. L. Miller
Keyword(s):  
Axial Stress ◽  
Boundary Value ◽  
Sufficient Conditions ◽  
Antiplane Shear ◽  
Shear Stresses ◽  
Elastic Solids ◽  
Shear Deformations ◽  
End Effects ◽  
Elastic Symmetry ◽  
Cross Sectional

Antiplane shear deformations of a cylindrical body, with a single displacement field parallel to the generators of the cylinder and independent of the axial coordinate, are one of the simplest classes of deformations that solids can undergo. They may be viewed as complementary to the more familiar plane deformations. Antiplane (or longitudinal) shear deformations have been the subject of the considerable recent interest in nonlinear elasticity theory for homogeneous isotropic solids. In contrast, for the linear theory of isotropic elasticity, such deformations are usually not extensively discussed. The purpose of the present paper is to demonstrate that for inhomogeneous anisotropic linearly elastic solids the antiplane shear problem does provide a particularly tractable and illuminating setting within which effects of anisotropy and inhomogeneity may be examined. We consider infinitesimal antiplane shear deformations of an inhomogeneous anisotropic linearly elastic cylinder subject to prescribed surface tractions on its lateral boundary whose only nonzero component is axial and which does not vary in the axial direction. In the absence of body forces, not all arbitrary anisotropic cylinders will sustain an antiplane shear deformation under such tractions. Necessary and sufficient conditions on the elastic moduli are obtained which do allow an antiplane shear. The resulting boundary value problems governing the axial displacement are formulated. The most general elastic symmetry consistent with an antiplane shear is described. There are at most 15 independent elastic coefficients associated with such a material. In general, there is a normal axial stress present, which can be written as a linear combination of the two dominant shear stresses. For a material with the cylindrical cross-section a plane of elastic symmetry (monoclinic, with 13 moduli), the normal stress is no longer present. For homogeneous materials, it is shown how the governing boundary value problem can be transformed to an equivalent isotropic problem for a transformed cross-sectional domain. Applications to the issue of assessing the influence of anisotropy and inhomogeneity on the decay of Saint-Venant end effects are described.

Microtensile Specimen Attachment and Shape—Finite Element Analysis

2008 ◽  
Vol 87 (1) ◽  
pp. 89-93 ◽  
Author(s):  
C.J. Soares ◽  
P.V. Soares ◽  
P.C.F. Santos-Filho ◽  
S.R. Armstrong
Keyword(s):  
Stress Distribution ◽  
Shear Stresses ◽  
Element Analysis ◽  
Cross Sectional ◽  
Surface Attachment ◽  
Testing Specimen ◽  
Testing Region ◽  
Number Of Faces ◽  
Von Mises ◽  
Specimen Shape

Microtensile bond strength values are influenced by specimen shape and attachment method to the gripping device during testing. We hypothesized that stress distribution inside the testing specimen is affected by microtensile specimen shape and attachment method. Rectangular, hourglass-, and dumbbell-shaped specimens, all with a 1 mm2 cross-sectional testing region, were modeled as indirect ceramic restorations luted to dentin. Three specimen attachments were investigated: (1) posterior surface; (2) posterior, superior, and lateral surfaces; and (3) all surfaces. Qualitative and quantitative analyses were carried out according to von Mises’ criteria. Stress analysis showed a direct correlation between attachment modes and stress distribution, with shear stresses observed in models with less surface attachment. Increasing the number of faces for specimen attachment to the metallic gripping device resulted in a more homogeneous and regular distribution of stress, with tensile stress concentrated at the adhesive interface. Dumbbell-shaped specimens showed improved stress distribution compared with rectangular and hourglass-shaped specimens.

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