Stress intensity factors around a crack parallel to a free surface of a half-plane

1994 ◽  
Vol 67 (2) ◽  
pp. 179-185 ◽  
Author(s):  
S. Itou
Keyword(s):  
Free Surface ◽  
Stress Intensity ◽  
Half Plane ◽  
Stress Intensity Factors ◽  
Intensity Factors

Mixed Mode Interface Cracks in a Bi-Material Half Plane and a Bi-Material Strip

1999 ◽  
Author(s):  
Haiying Huang ◽  
George A. Kadomateas ◽  
Valeria La Saponara
Keyword(s):  
Stress Intensity ◽  
Free Boundary ◽  
Half Plane ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Infinite Strip ◽  
Infinite Plane ◽  
Intensity Factors ◽  
Interface Cracks ◽  
Mode Stress

Abstract This paper presents a method for determining the dislocation solution in a bi-material half plane and a bi-material infinite strip, which is subsequently used to obtain the mixed-mode stress intensity factors for a corresponding bi-material interface crack. First, the dislocation solution in a bi-material infinite plane is summarized. An array of surface dislocations is then distributed along the free boundary of the half plane and the infinite strip. The dislocation densities of the aforementioned surface dislocations are determined by satisfying the traction-free boundary conditions. After the dislocation solution in the finite domain is achieved, the mixed-mode stress intensity factors for interface cracks are calculated based on the continuous dislocation technique. Results are compared with analytical solution for homogeneous anisotropic media.

Dynamic Stress Intensity Factors for an Inclined Subsurface Crack

1984 ◽  
Vol 51 (4) ◽  
pp. 773-779 ◽  
Author(s):  
W. Lin ◽  
L. M. Keer ◽  
J. D. Achenbach
Keyword(s):  
Free Surface ◽  
Stress Intensity ◽  
Integral Equations ◽  
Stress Intensity Factors ◽  
Wave Equations ◽  
Harmonic Excitation ◽  
Subsurface Crack ◽  
Intensity Factors ◽  
Dynamic Stress Intensity Factors ◽  
Time Harmonic

Stress intensity factors are computed for an inclined subsurface crack in a half space, whose surface is subjected to uniform time-harmonic excitation. The problem is analyzed by determining displacement potentials that satisfy reduced wave equations and specified boundary conditions. The formulation of the problem leads to a system of coupled integral equations for the dislocation densities. The numerical solution of the integral equations leads directly to the stress intensity factors. Curves are presented for the ratios of the elastodynamic and the corresponding elastostatic Mode-I and Mode-II stress intensity factors for various frequencies and various inclinations of the crack with the free surface. For small angles of inclination with the free surface and large crack length-to-depth ratios, strong resonance vibrations of the layer between the crack and the free surface may arise.

Stress Intensity Factor Interaction for Subsurface to Surface Flaw Transformations Under Stress Concentration Fields

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Pierre Dulieu ◽  
Valéry Lacroix ◽  
Kunio Hasegawa
Keyword(s):  
Stress Intensity Factor ◽  
Free Surface ◽  
Stress Intensity ◽  
Stress Concentration ◽  
Intensity Factor ◽  
Stress Intensity Factors ◽  
Concentration Field ◽  
Surface Flaw ◽  
Intensity Factors ◽  
Surface Proximity

If a single subsurface flaw is detected that is close to a component's free surface, a flaw-to-surface proximity rule is used to determine whether the flaw should be treated as a subsurface flaw, or transformed to a surface flaw. The transformation from subsurface to surface flaw is adopted as flaw-to-surface proximity rules in all fitness-for-service (FFS) codes. These proximity rules are applicable when the component's free surface is without a stress concentration. On the other hand, subsurface flaws have been found under notches, such as roots of bolts, toes in welded joints, or geometrical discontinuities of components. The stress intensity factors of the subsurface flaws are affected by the stress concentrations caused by the notches. The stress intensity factor of the subsurface flaw increases with increasing stress concentration factor of the notch and decreasing ligament distance between tip of the subsurface flaws and the notch, for a given notch width. Such subsurface flaws are transformed to surface flaws at a distance from the notch tip for conservative evaluations. This paper shows the interactions of stress intensity factors of subsurface flaws under stress concentration fields. Based on the interaction, a flaw-to-surface proximity criterion is proposed for a circular flaw under the stress concentration field induced by a notch.

A Surface Crack in a Graded Medium Under General Loading Conditions

2002 ◽  
Vol 69 (5) ◽  
pp. 580-588 ◽  
Author(s):  
S. Dag ◽  
F. Erdogan
Keyword(s):  
Stress Intensity ◽  
Half Plane ◽  
Stress Intensity Factors ◽  
Surface Crack ◽  
Crack Surface ◽  
Local Perturbation ◽  
Local Problem ◽  
Loading Conditions ◽  
Intensity Factors ◽  
Perturbation Problem

In this study the problem of a surface crack in a semi-infinite elastic graded medium under general loading conditions is considered. It is assumed that first by solving the problem in the absence of a crack it is reduced to a local perturbation problem with arbitrary self-equilibrating crack surface tractions. The local problem is then solved by approximating the normal and shear tractions on the crack surfaces by polynomials and the normalized modes I and II stress intensity factors are given. As an example the results for a graded half-plane loaded by a sliding rigid circular stamp are presented.

Mixed-Mode Stress Intensity Factors in a Homogeneous Orthotropic Medium Loaded by a Frictional Sliding Rigid Flat Stamp

2018 ◽  
Vol 774 ◽  
pp. 179-184 ◽  
Author(s):  
K.B. Yilmaz ◽  
Mehmet Ali Güler ◽  
Boray Yildirim
Keyword(s):  
Stress Intensity ◽  
Half Plane ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Orthotropic Materials ◽  
Geometrical Parameters ◽  
Orthotropic Medium ◽  
Intensity Factors ◽  
Flat Punch ◽  
Mode Stress

In this study, the crack problem for a homogeneous orthotropic medium loaded by a sliding rigid flat punch is considered. The homogeneous orthotropic medium is assumed to be a half-plane and is subjected to both normal and tangential forces through the sliding action of the punch. The crack on the homogeneous orthotropic medium is supposed to a depth of and is parallel to the direction of the normal force. The effect of the geometrical parameters and coefficient of friction on the mixed-mode stress intensity factors (mode I and mode II) is investigated using a computational approach using the finite element method. Augmented Lagrange method is used for the contact algorithm between the rigid flat punch and homogeneous orthotropic half-plane. This study may provide insight to the engineers in understanding the crack mechanisms in orthotropic materials in a comprehensive way and to identify early crack propagations under frictional loadings accurately.

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