A number of current practices in fracture mechanics which use quantities near a crack tip to make conclusions about response at the crack tip itself are examined. Specifically these include: stress and displacement matching to estimate stress intensity factors, monitoring local stress and strain values to predict fracture, and both crack opening angle and crack opening displacement as fracture criteria. By means of a pair of counter applications, all of these procedures are demonstrated to have the potential of leading to completely incorrect conclusions. An understanding of what causes this inadequate performance then indicates that such procedures may be unreliable in general and prompts suggestions as to alternatives.RésuméOn examine diverses pratiques courantes en Mécanique de Rupture qui font usage de grandeurs paramétriques au voisinage de l'extrémité d'une fissure pour tirer des conclusions sur ce qui se passe à cette extrémité même. Ces grandeurs sont notamment: les valeurs de la contrainte et du déplacement correspondant à un facteur d'intensité de contrainte estimé, l'enregistrement des contraintes et déplacements locaux en vue de prédire la rupture, et l'angle et le déplacement d'ouverture d'une fissure en tant que critères de rupture.En considérant une paire d'applications divergentes, on démontre que toutes ces procédures risquent d'entraîner des conclusions complètement incorrectes.Une analyse des causes de ces inadéquations montre que ces procédures peuvent se révéler peu fiables en général, et conduit à des suggestions de procédures alternatives.
[1]
D. Forbes.
The Iron and Steel Institute
,
1871,
Nature.
[2]
Harold Liebowitz,et al.
Crack border stress and displacement equations revisited
,
1977
.
[3]
Lf Impellizzeri,et al.
Cyclic Stress-Strain and Plastic Deformation Aspects of Fatigue Crack Growth
,
1977
.
[4]
S. Chan,et al.
On the Finite Element Method in Linear Fracture Mechanics
,
1970
.
[5]
B. F. Backman,et al.
Recent advances in computerized aerospace structural analysis and design
,
1977
.
[6]
John W. Hutchinson,et al.
Singular behaviour at the end of a tensile crack in a hardening material
,
1968
.
[7]
H. Andersson.
A finite-element representation of stable crack-growth
,
1973
.
[8]
G. B. Sinclair,et al.
A simple yet accurate finite element procedure for computing stress intensity factors
,
1982
.
[9]
J. D. Eshelby,et al.
The force on an elastic singularity
,
1951,
Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.
[10]
James C. Newman,et al.
Stress-intensity factors for a wide range of semi-elliptical surface cracks in finite-thickness plates
,
1979
.
[11]
J. Reddy,et al.
Direct prediction of fracture for two-dimensional plane stress structures
,
1980
.
[12]
C. C. Chamis,et al.
Failure Criteria for Filamentary Composites
,
1969
.