scholarly journals Subsurface Cracks Under Conditions of Slip, Stick, and Separation Caused by a Moving Compressive Load

1987 ◽  
Vol 54 (2) ◽  
pp. 393-398 ◽  
Author(s):  
S. D. Sheppard ◽  
J. R. Barber ◽  
M. Comninou
Keyword(s):  
Integral Equation ◽  
Stress Intensity ◽  
Coulomb Friction ◽  
Compressive Load ◽  
Mode I ◽  
Subsurface Crack ◽  
Intensity Factors ◽  
Subsurface Cracks ◽  
Load Location ◽  
Crack Faces

The Mode I and II stress intensity factors (KI, KII) at the two tips of a subsurface crack subjected to a moving compressive load are studied. Coulomb friction along the crack faces results in a number of history dependent slip-stick configurations and nonsymmetric variation in KI and KII. The formulation used to study this variation involves a singular integral equation in two variables which must be solved numerically, and because of the history dependence, requires an incremental solution. Crack lengths and coefficients of friction that result in as many as three zones for any load location are considered in this paper, while a previous paper (Sheppard et al., in press) was limited to configurations involving two zones only.

scholarly journals Short Subsurface Cracks Under Conditions of Slip and Stick Caused by a Moving Compressive Load

1985 ◽  
Vol 52 (4) ◽  
pp. 811-817 ◽  
Author(s):  
S. Sheppard ◽  
J. R. Barber ◽  
M. Comninou
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Coulomb Friction ◽  
Compressive Load ◽  
Rolling Contact ◽  
Intensity Factors ◽  
Subsurface Cracks ◽  
Spalling Failure ◽  
Load Location ◽  
Crack Faces

The mechanism of spalling failure in rolling contact is modeled by an elastic half-plane with a subsurface crack parallel to the surface, loaded by a compressive normal force which moves over the surface. Coulomb friction at the crack faces reduces the Mode II Stress Intensity Factors and results in a number of history-dependent slip-stick configurations. The formulation used to study these involves a singular integral equation in two variables which must be solved numerically, and because of the history dependence, requires in an incremental solution. Only crack lengths and coefficients of friction that result in a maximum of two slip or stick zones for any load location are considered in this paper. It is found that the maximum range of stress intensity factors occurs at the trailing crack tip.

Elastodynamic Stress-Intensity Factors for a Crack Near a Free Surface

1981 ◽  
Vol 48 (3) ◽  
pp. 539-542 ◽  
Author(s):  
J. D. Achenbach ◽  
R. J. Brind
Keyword(s):  
Stress Intensity ◽  
Half Space ◽  
Stress Intensity Factors ◽  
Elastic Half Space ◽  
Mode I ◽  
Dimensionless Frequency ◽  
Subsurface Crack ◽  
Intensity Factors ◽  
Time Harmonic ◽  
Crack Tips

Elastodynamic Mode I and Mode II stress-intensity factors are presented for a subsurface crack in an elastic half space. The plane of the crack is normal to the surface of the half space. The half space is subjected to normal and tangential time-harmonic surface tractions. Numerical results show the variation of KI and KII at both crack tips, with the dimensionless frequency and the ratio a/b, where a and b are the distances to the surface from the near and the far crack tips, respectively. The results are compared with corresponding results for a crack in an unbounded solid.

An Analysis of a Near-Surface Crack Branching Under a Rigid Indenter

1999 ◽  
Vol 122 (1) ◽  
pp. 23-29 ◽  
Author(s):  
David J. Mukai
Keyword(s):  
Coulomb Friction ◽  
Crack Depth ◽  
Hertzian Contact ◽  
Crack Branching ◽  
Mode I ◽  
Subsurface Crack ◽  
Intensity Factors ◽  
Near Surface ◽  
Straight Crack ◽  
Surface Conditions

A near surface branching subsurface crack under a rigid cylindrical indenter is analyzed by a complex variable 2-D elasticity formulation. This analysis focuses on the mode II stress intensity factors (SIF) of a straight crack vs. the mode I SIF of a branched crack. The contact portion of the analysis is limited to a Hertzian contact under simple Coulomb friction. The effects of crack depth and length are examined and it is found that for small indenter footprints, as a crack grows parallel to the surface, conditions favor mode I branching toward the surface. [S0742-4787(00)00401-X]

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.

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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