Stress intensity factors in fretting fatigue

1979 ◽  
Vol 14 (1) ◽  
pp. 1-6 ◽  
Author(s):  
D P Rooke ◽  
D A Jones
Keyword(s):  
Stress Intensity ◽  
Crack Length ◽  
Stress Intensity Factors ◽  
Polynomial Function ◽  
Fretting Fatigue ◽  
Mode I ◽  
Mode Ii ◽  
Shear Stresses ◽  
Intensity Factors ◽  
Tangential Forces

Solutions are derived for mode I and mode II stress intensity factors for a crack at the edge of a sheet subjected to localized fretting forces. Both normal and tangential forces are considered. These solutions are approximated by a polynomial function of crack length, which is then used as a Green's function to derive stress intensity factors for arbitrary distributions of tensile and shear stresses at the edge of the sheet.

Estimation of Mixed-Mode Stress Intensity Factors with Presence of the Confinement Parameters T-Stress and A3

2016 ◽  
Vol 18 ◽  
pp. 52-57
Author(s):  
Lahouari Fodil ◽  
Abdallah El Azzizi ◽  
Mohammed Hadj Meliani
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Compact Tension ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Intensity Factors ◽  
Element Analysis ◽  
T Stress

A failure criterion is proposed for ductile fracture in U-notched components under mixed mode static loading. The Compact Tension Shear (CTS) is the preferred test specimen used to determine stress intensity factor in the mode I, mode II and the mixed-mode fracture. In this work, the mode I and mode II stress intensity factors were computed for different notch ratio lengths 0.1<a/W<0.7, of the inner radius of notch 0.25mm<ρ<4mm and load orientation angles 0°<α< 90° using finite element analysis. However, a review of numerical analysis results reveals that the conventional fracture criteria with only stress intensity factors (NSIFs) Kρ first term of Williams’s solution provide different description of stress field around notch zone comparing with results introduce the second and third parameter T-stress and A3.

Reliability Analysis of the Cracked Ag-SU8 Interface on the Channel Wall in a Micro-PEMFC

2006 ◽  
Author(s):  
Chi-Hui Chien ◽  
Yi-San Shih ◽  
Shou-Shing Hsieh ◽  
Huang-Hsiu Tsai ◽  
Chih-Wei Lin ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Crack Length ◽  
Stress Intensity Factors ◽  
Channel Wall ◽  
Crack Tip ◽  
Electrochemical Process ◽  
Shear Stresses ◽  
Intensity Factors ◽  
Compressive Stresses ◽  
And Performance

The efficiency of the fuel cell depends on both the kinetics of the electrochemical process and performance of the components. The main aim of this research is to analysis the reliability of the cracked Ag-SU8 interface on the channel wall in a micro-PEMFC. An existed surface crack on the channel wall subjected to the flow induced compressive stresses and shear stresses will propagate and lead to the spall formation. In this paper, at first, the flow induced compressive and shear stresses are obtained through simulation of stress state and flow-field in the micro-channel by commercial package software ANSYS® 8.0. Then, the stresses arising at the crack tip due to flow induced compressive and shear stresses can be calculated and characterized by the mode I and II stress intensity factors (SIF), KI and KII, respectively. Finally, the KI and KII stress intensity factors at the crack tip are computed for the different crack sizes and loadings. The results show that the inlet pressure and crack length affect the stress intensity factors more than the inlet velocity does. Also, the results show that as the crack length increases, the value of KI will increase, but the value of KII decreases slightly.

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.

Fracture Mechanics Analysis of Functionally Graded Material Based on Finite Element Method

2012 ◽  
Vol 195-196 ◽  
pp. 787-790
Author(s):  
Bo He ◽  
Hong Cai Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Functionally Graded ◽  
Mode I ◽  
Mode Ii ◽  
Intensity Factors ◽  
Graded Material ◽  
Crack Angle

In this paper, the fracture problem of functionally graded material (FGM) was studied, and the shear modulus was assumed to be an exponential function. The influences of inhomogeneous parameter, crack size and crack angle on the stress intensity factors have been analyzed by the finite element method. The results indicated that the stress intensity factors of mode I decreased with the increasing of the crack angle, the stress intensity factors of mode II increased with the increasing of the crack angle, and the crack stress intensity factor of mode I and mode II decreased with the increasing of the inhomogeneous parameters at crack tips, which was of certain directive significance for the FGM design and manufacture in the actual engineering.

Stress Intensity Factors for a Vertical Surface Crack in Polyethylene Subject to Rolling and Sliding Contact

1998 ◽  
Vol 120 (6) ◽  
pp. 778-783 ◽  
Author(s):  
A. W. Eberhardt ◽  
B. S. Kim
Keyword(s):  
Stress Intensity ◽  
Crack Length ◽  
Stress Intensity Factors ◽  
Surface Crack ◽  
Sliding Friction ◽  
Sliding Contact ◽  
Mode I ◽  
Surface Cracks ◽  
Intensity Factors ◽  
Load Location

Pitting wear is a dominant form of polyethylene surface damage in total knee replacements, and may originate from surface cracks that propagate under repeated tribological contact. In the present study, stress intensity factors, KI, and KII, were calculated for a surface crack in a polyethylene-CoCr-bone system in the presence of rolling or sliding contact pressures. Variations in crack length and load location were studied to determine probable crack propagation mechanisms and modes. The crack tip experienced a wide range of mixed-mode conditions that varied as a function of crack length, load location, and sliding friction. Positive KI values were observed for shorter cracks in rolling contact and for all crack lengths when the sliding load moved away from the crack. KII was greatest when the load was directly adjacent to the crack (g/a = ±1), where coincidental Mode I stresses were predominantly compressive. Sliding friction substantially increased both KImax and KIImax. The effective Mode I stress intensity factors, Keff, were greatest at g/a = ±1, illustrating the significance of high shear stresses generated by loads adjacent to surface cracks. Keff trends suggest mechanisms for surface pitting by which surface cracks propagate along their original plane under repeated reciprocating rolling or sliding, and turn in the direction of sliding under unidirectional sliding contact.

scholarly journals Effect of Mechanical Mismatch on the Stress Intensity Factors of Inclined Cracks under Mode I Tension Loading

2015 ◽  
Vol 773-774 ◽  
pp. 129-133
Author(s):  
Mohd Azwir Azlan ◽  
Al Emran Ismail
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Mode I ◽  
Mode Ii ◽  
Intensity Factors ◽  
Finite Element Program ◽  
Element Program ◽  
Plain Strain ◽  
Tension Loading ◽  
Inclined Cracks

This paper presents numerical analysis of stress intensity factors (SIFs) of inclined cracks due to mechanical mismatches. According to literature survey, tremendous amounts of SIFs can be found elsewhere. However, the SIFs for inclined cracks are difficult to obtain especially when mechanical mismatch at the crack interface are considered. ANSYS finite element program is used to model the cracks embedded in plain strain plates. The cracks are oriented at the interface between two different materials and subjected to mode I tension loading. It is showed that when mechanical mismatches are introduced the mode I SIFs reduced and on the other hand mode II SIFs increased. When the cracks are inclined, the mode I SIFs diverged but it is not for mode II SIFs and gradually increased when compared with the normal cracks.

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