Crack Propagation in Rolling Line Contacts

1992 ◽  
Vol 114 (4) ◽  
pp. 690-697 ◽  
Author(s):  
H. Salehizadeh ◽  
N. Saka
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Stress Intensity Factors ◽  
Mode Ii ◽  
Pure Mode ◽  
Intensity Factors ◽  
Crack Face ◽  
Normal Loading ◽  
Line Contacts ◽  
Crack Growth Model

The stress intensity factors for short straight and branched subsurface cracks subjected to a Hertzian loading are calculated by the finite element method. The effect of crack face friction on stress intensity factors is considered for both straight and branched cracks. The calculations show that the straight crack is subjected to pure mode II loading, whereas the branched crack is subjected to both mode I and mode II, with ΔKI/ΔKII < 0.25. Although KI is small, it strongly influences KII by keeping the branched crack faces apart. Based on the ΔKII values and Paris’s crack growth model, the number of stress reversals required to grow a crack in a rolling component from an initial threshold length to the final spalling length was estimated. It was found that the crack propagation period is small compared with the expected bearing fatigue life. Therefore, crack propagation is not the rate controlling factor in the fatigue failure of bearings operating under normal loading levels.

Effect of Confining Pressure on Stress Intensity Factors for Cracked Brazilian Disk

2015 ◽  
Vol 07 (03) ◽  
pp. 1550051 ◽  
Author(s):  
Wen Hua ◽  
Jigang Xu ◽  
Shiming Dong ◽  
Jizhou Song ◽  
Qingyuan Wang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Confining Pressure ◽  
Mode Ii ◽  
Pure Mode ◽  
Intensity Factors ◽  
Brazilian Disk ◽  
Mode Ii Crack

An analytical model, verified by the finite element method, is developed to study the effect of confining pressure on stress intensity factors for the cracked Brazilian disk. The closed-form expressions for stress intensity factors under both confining pressure and diametric forces are obtained based on the weight function method. The results show that the confining pressure has no effect on the mode II stress intensity factor; however, the mode I stress intensity factor decreases with the increase of confining pressure and the change may be above 100% for a large confining pressure. In addition, the effect of confining pressure on the loading condition of pure mode II crack is also investigated. It is shown that the critical loading angle for pure mode II crack decreases as the confining pressure increases. Depending on the magnitude of confining pressure, the failure problem of a disk may be no longer a pure fracture problem. These results have established the theoretical foundation to measure the fracture toughness of materials under confining pressure.

Computational modelling of shot-peening effects on crack propagation under fretting fatigue

2003 ◽  
Vol 38 (6) ◽  
pp. 495-506 ◽  
Author(s):  
S Shkarayev ◽  
S Mall
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Shot Peening ◽  
Experimental Studies ◽  
Computational Modelling ◽  
Fretting Fatigue ◽  
Intensity Factors ◽  
Crack Growth Model

Recent experimental studies have demonstrated fretting fatigue life enhancement of titanium alloy Ti-6A1–4V specimens after treatment by shot-peening. Because of complexities in tracking crack growth under fretting conditions experimentally, the present work describes computational modelling for crack propagation behaviour in specimens with and without shot-peening. A crack growth model is combined with a finite element submodelling technique to assess the crack trajectory and crack propagation life in the specimens under fretting fatigue. A parametric numerical analysis has been performed to investigate crack trajectories and stress intensity factors along the crack path under different loading conditions. Obtained results revealed the features of the crack growth trajectory and stress intensity factors in the presence of residual stresses from shotpeening. These results also demonstrated a significant (2–3 times) increase in the crack propagation life of shot-peened specimens relative to virgin specimens (i.e. without shot-peening), which is in agreement with experimental observations.

Three-Dimensional Mode Separation to Obtain Stress Intensity Factors

2006 ◽  
Author(s):  
Pei Gu ◽  
R. J. Asaro
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Stress Intensity Factors ◽  
Three Dimensional ◽  
Integral Approach ◽  
Mode I ◽  
Mode Ii ◽  
Intensity Factors ◽  
Mode Iii ◽  
Mode Separation

For mixed-mode loading at a crack tip under small-scale yielding condition, mode I, mode II and mode III stress intensity factors control the crack propagation. This paper discusses three-dimensional mode separation to obtain the three stress intensity factors using the interaction integral approach. The 2D interaction integral approach to obtain mode I and mode II stress intensity factors is derived to 3D arbitrary crack configuration for mode I, mode II and mode III stress intensity factors. The method is implemented in a finite element code using domain integral method and numerical examples show good convergence for the domains around the crack tip. A complete solution for the three stress intensity factors is obtained for a bar with inclined crack face to the cross-section from numerical calculations. The solution for the bar is plotted into curves in terms of a set of non-dimensional parameters for practical engineering purpose. From the solution, mode mixity along the crack front and its implication to the direction of crack propagation is discussed.

Effects of Thickness on Fracture Toughness of Carbon/Polyester Composite

2011 ◽  
Vol 471-472 ◽  
pp. 886-891
Author(s):  
Mohammad Hossein Heydari ◽  
Naghdali Choupani
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Mode I ◽  
Mode Ii ◽  
Pure Mode ◽  
Intensity Factors ◽  
Interlaminar Fracture ◽  
Polyester Composite

The aim of this paper is to evaluate interlaminar fracture toughness and non dimensional stress intensity factors of woven Carbon-Polyester composite based on numerical and experimental methods. A modified version of Arcan specimen was employed to conduct a mixed-mode fracture test using a special loading device. By changing the loading angle, α, from 0° to 90°, mode-I, mode-II and all mixed-mode data were created. The finite element analysis was performed with Abaqus software. The interaction j-integral was used to separate the mixed mode stress intensity factors and energy release rate at the crack tip under different loading conditions and different thickness of specimens. The results of fracture toughness tests revealed that the interlaminar fracture of composite is strong under the shearing-mode loading but weaker to the opening- mode loading. It can be seen that by increasing the thickness of the composite specimen, non dimensional stress intensity factors for pure mode I (α=0°) and pure mode II (α=90° ) loading conditions were decreased.

The effect of friction on crack propagation in the dovetail fixings of compressor discs

1998 ◽  
Vol 212 (3) ◽  
pp. 171-181 ◽  
Author(s):  
R L Burguete ◽  
E A Patterson
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Coefficient Of Friction ◽  
Stress Intensity Factors ◽  
Mode I ◽  
Mode Ii ◽  
Intensity Factors ◽  
The Coefficient Of Friction

Stress frozen photoelasticity has been used to model dovetail compressor blade fixings. During loading a known coefficient of friction was applied and the effect of the variation of this parameter on crack initiation and propagation was investigated. Data were recorded from the specimen using an automated computer aided polariscope based on the method of phase stepping. Isochromatic and isoclinic data were collected and used to determine the stress distribution, the stress intensity factor and the crack propagation direction. The method to predict the direction of crack propagation has been improved so that photoelastic data can be used reliably for this purpose. Three values of the coefficient of friction were used for two different dovetail geometries. It was found that the initial values of the mode II stress intensity factors were higher for a lower friction coefficient. An increase in crack length produced a corresponding decrease in the mode I stress intensity factor and a decrease in the mode II value. It was concluded that the coefficient of friction influenced crack growth at all stages of crack growth because it affects the relative levels of the mode I and mode II stress intensity factors. This has an effect on the direction of the maximum principal stress direction and so on the direction of crack propagation.

Mixed-mode stress intensity factors for inclined cracks in round bars

1993 ◽  
Vol 28 (4) ◽  
pp. 257-262 ◽  
Author(s):  
T H Hyde ◽  
N A Warrior
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Mode I ◽  
Mode Ii ◽  
Pure Mode ◽  
Intensity Factors ◽  
Analysis Technique ◽  
Mode Stress ◽  
Photoelastic Stress ◽  
Inclined Cracks

The frozen-stress photoelastic stress analysis technique is used to obtain the mode I and mode II stress-intensity factors for cracks in round bars. The bars, which are subjected to bending, contain cracks inclined to the transverse planes of the bars. Results for inclinations of 45, 60, 75, and 90 degress are obtained. Crack depths of 0.3 ×, 0.5 ×, and 0.7 × the diameter are investigated. The results are normalized so that they can be applied to similar shaped cracks in bars of any diameter and material subjected to bending. The agreement with previously published results (for the pure mode I case) is very good, i.e., within 3 percent. The choice of normalizing parameters makes the normalized mode I and mode II stress-intensity factor relatively insensitive to the crack inclination. The mode II stress-intensity factors are practically constant along the crack fronts whereas the mode I stress intensity factors fall sharply near the ends of the crack, i.e., where they break the surface of the bar.

Linear-Elastic and Elastoplastic Mode II and III Crack Tip Stress-Strain Fields in Cylindrical Specimens with Circumferential Crack

2009 ◽  
Vol 417-418 ◽  
pp. 321-324 ◽  
Author(s):  
Jana Horníková ◽  
Pavel Šandera ◽  
Jaroslav Pokluda
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Front ◽  
Crack Tip ◽  
Mode Ii ◽  
Pure Mode ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Circumferential Crack ◽  
Crack Tip Opening

A numerical analysis by means of the ANSYS code was performed in order to identify the ratio of both stress intensity factors and crack tip opening displacements for a cylindrical specimen with circumferential V-notch loaded by remote pure shear stress. This kind of loading produces pure mode II and III loading in four points on the circumferential crack front while the mix mode II+III exists in all other crack front points. In the linear-elastic range, the ratio of maximum values of mode III and mode II stress intensity factors was found to be . On the other hand, the ratio of crack tip opening displacements in the elastoplastic range approaches . These results can be used for the construction of fatigue crack growth rate curves in austenitic and ferritic steels measured in the near-threshold and near-fracture regions by means of a special testing device.

Stress intensity factors in novel specimens for crack propagation under loading conditions II+III in polymers

2020 ◽  
Author(s):  
Ondrej Slávik ◽  
Pavel Hutař ◽  
Michael Berer ◽  
Anja Gosch ◽  
Tomáš Vojtek ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Stress Intensity Factors ◽  
Loading Conditions ◽  
Intensity Factors

Analysis of Crack Propagation in Roller Bearings Using the Boundary Integral Equation Method—A Mixed-Mode Loading Problem

1988 ◽  
Vol 110 (3) ◽  
pp. 408-413 ◽  
Author(s):  
L. J. Ghosn
Keyword(s):  
Integral Equation ◽  
Stress Intensity ◽  
Crack Propagation ◽  
Boundary Integral Equation ◽  
Stress Intensity Factors ◽  
High Speed ◽  
Roller Bearing ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Intensity Factors

Crack propagation in a rotating inner raceway of a high-speed roller bearing is analyzed using the boundary integral method. The model consists of an edge plate under plane strain condition upon which varying Hertzian stress fields are superimposed. A multidomain boundary integral equation using quadratic elements was written to determine the stress intensity factors KI and KII at the crack tip for various roller positions. The multidomain formulation allows the two faces of the crack to be modeled in two different subregions making it possible to analyze crack closure when the roller is positioned on or close to the crack line. KI and KII stress intensity factors along any direction were computed. These calculations permit determination of crack growth direction along which the average KI times the alternating KI is maximum.

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