Aircraft and pressure vessel components experience stresses that are negative biaxial or multiaxial in nature. Biaxiality is defined as the ratio of stress applied parallel and normal to the crack front. In recent years, many experimental studies have been conducted on fatigue crack growth (FCG) under various biaxial loading conditions. Biaxial loadings affect crack front stresses and strains, fatigue crack growth rate and direction, and crack tip plastic zone size and shape. Many of these studies have focused on positive biaxial loading cases. No conclusive study has been reported out yet that accurately quantifies the influence of negative biaxiality on fatigue crack growth behavior. Lacking validation, implementation on real life problems remains questionable. To ensure safe and optimum designs, it is necessary to better understand and quantify the effect of negative biaxial loading on fatigue crack behavior. This paper presents the results of a study to quantify the effect of biaxial load cases ranging from B = −0.5 to 1.0 on fatigue crack growth behavior. Also, a simplified approach is presented to incorporate the effect of biaxiality into da/dN curves generated from uniaxial loading using an analytical approach without conducting expensive biaxial crack growth testing. Sensitivity studies were performed with existing test data available for AA2014-T6 aluminum alloy. Detailed elastic-plastic finite element analyses were performed using the different stress ranges and stress ratios with various crack sizes and shapes on notched and unnotched geometries. Constant amplitude loads were applied for the current work and comparison studies were made between uniaxial and different biaxial loading cases. It was observed from the study that negative biaxiality has a very pronounced effect on the crack growth rate and direction for AA2014-T6 if the externally applied load equal to 30% of the yield strength as compared with 40% of externally applied load for steel alloy quoted in the literature.

References

References
1.
Liu
,
A. F.
, and
Dittmer
,
D. F.
,
1978
, “
Effect of Multiaxial Loading on Crack Growth, Volumes 1–3
,”
Air Force Wright Patterson, Aeronautical Lab
,
Ohio
, Report No. AFFDL-TR-78-175.
2.
Shylyannikov
,
V. N.
,
2002
,
Elastic-Plastic Mixed-Mode Fracture Criteria and Parameters
,
Springer
,
New York
.
3.
McClung
,
R. C.
,
1989
, “
Closure and Growth of Mode I Cracks in Biaxial Fatigue
,”
Fatigue Fract. Eng. Mater. Struct.
,
12
, pp.
447
460
.10.1111/j.1460-2695.1989.tb00552.x
4.
Lam
,
Y. C.
,
1993
, “
Fatigue Crack Growth Under Biaxial Loading
,”
Fatigue Fract. Eng. Mater. Struct.
,
16
(
4
), pp.
429
440
.10.1111/j.1460-2695.1993.tb00098.x
5.
Kim
,
Y. J.
,
Chung
,
K. H.
,
Kim
,
J. S.
, and
Young
,
J. K.
,
2005
, “
Effect of Biaxial Loads on Elastic-Plastic J and Crack-Tip Constraint for Crack Plate: Finite Element Study
,”
Int. J. Fract.
,
130
, pp.
803
825
.10.1007/s10704-004-2550-2
6.
Socie
,
D. F.
, and
Marquis
,
G. B.
,
2000
,
Multiaxial Fatigue
,
Society of Automotive Engineers
, Troy, MI. Available at http://books.sae.org/r-234/
7.
O'Dowd
,
N. P.
,
Kolednik
,
O.
, and
Naumenko
,
V. P.
,
1999
, “
Elastic-Plastic Analysis of Biaxially Loaded Center-Cracked Plates
,”
Int. J. Solids Struct.
,
36
, pp.
5639
5661
.10.1016/S0020-7683(98)00257-1
8.
Brown
,
M. W.
, and
Miller
,
K. J.
, eds.,
1985
, “
Mode-1 Fatigue Crack Growth Under Biaxial Stresses at Room and Elevated Temperature
,”
Multiaxial Fatigue
,
American Society for Testing and Materials
,
Philadelphia
, pp.
135
152
, Paper No. ASTM STP 853.
9.
Rhodes
,
D.
, and
Radon
,
J. C.
,
1982
, “
Effect of Local Stress Biaxiality on the Behavior of Fatigue Crack Growth Test Specimens
,”
Multiaxial Fatigue
,
K. J.
Miller
and
M. W.
Brown
, eds.,
American Society for Testing and Materials
,
Philadelphia
, pp.
153
163
, Paper No. ASTM STP 853.
10.
Richard
,
H. A.
,
Fulland
,
M.
, and
Sander
,
M.
,
2005
, “
Theoretical Crack Path Prediction
,”
Fatigue Fract. Eng. Mater. Struct.
,
28
, pp.
3
12
.10.1111/j.1460-2695.2004.00855.x
11.
Seibi
,
A. C.
, and
Zamrik
,
S. Y.
,
2003
, “
Prediction of Crack Initiation Direction for Surface Flaws Under Biaxial Loading
,”
ASME J. Pressure Vessel Technol.
,
125
, pp.
65
70
.10.1115/1.1521712
12.
Hopper
,
C. D.
, and
Miller
,
K. J.
,
1977
, “
Fatigue Crack Propagation in Biaxial Stress Fields
”,
J. Strain Anal.
,
12
(
1
), pp.
23
28
.10.1243/03093247V121023
13.
ansys V13
,
2009
,
Chapter on Fracture Mechanics
,
Ansys Manual
,
Canonsburg, PA
.
14.
Gosz
,
M.
, and
Moran
,
B.
,
2002
, “
An Interaction Energy Integral Method for Computation of Mixed-Mode Stress Intensity Factors Along Non-Planar Crack Fronts in Three Dimensions
,”
Eng. Fract. Mech.
,
69
, pp.
299
319
.10.1016/S0013-7944(01)00080-7
15.
Huber
,
O.
,
Nickel
,
J.
, and
Kuhn
,
G.
,
1993
, “
On the Decomposition of the J-Integral for 3D Crack Problems
,”
Int. J. Fract.
,
64
, pp.
339
348
.10.1007/BF00017849
16.
NASMAT Material Database
,
2005
, NASGRO 5.1, Southwest Research Institute, San Antonio, TX.
18.
Brocks
,
W.
, and
Scheider
,
I.
,
2001
, “
Numerical Aspects of the Path-Dependence of the J-Integral in Incremental Plasticity
,” GKSS Germany, Technical Report No. GKSS/WMS/2001/08.
19.
Cherepanov
,
C. P.
,
1967
, “
Crack Propagation in Continuous Media
,”
Appl. Math. Mech.
31
, pp.
476
488
.
20.
Rice
,
J. R.
,
1968
, “
A Path Independent Integral and the Approximate Analysis of Strain Concentration by Notches and Cracks
,”
ASME J. Appl. Mech.
,
35
(2), pp.
379
386
.10.1115/1.3601206
21.
Lambert
,
Y.
,
Saillard
,
P.
, and
Bathias
,
C.
,
1988
, “
Application of the J Concept to Fatigue Crack Growth in Large Scale Yielding
,”
Fracture Mechanics: Nineteenth Symposium
,
T. A.
Cruse
, ed.,
American Society for Testing and Materials
,
Philadelphia
, pp.
318
329
, Paper No. ASTM STP 969.
22.
Gasiak
,
G.
, and
Rozumek
,
D.
,
2004
, “
ΔJ—Integral Range Estimation for Fatigue Crack Growth Rate Description
,”
Int. J. Fatigue
,
26
, pp.
135
140
.10.1016/S0142-1123(03)00111-7
23.
Mehta
,
H. S.
, and
Ranganath
,
S.
,
1982
, “
Environmental Fatigue Crack Growth Based on Elastic-Plastic Fracture Mechanics
,” ASME Paper No. 82-PVP-23.
24.
Dowling
,
N. E.
, and
Begley
,
J. A.
,
1976
, “
Fatigue Crack Growth During Gross Plasticity and the J-Integral
,”
Mechanics of Crack Growth
,
American Society for Testing and Materials
,
Philadelphia
, pp.
82
103
, Paper No. ASTM STP 590.
25.
Leslie
,
B.-S.
, and
Yehuda
,
V.
,
1991
, “
Application of the Cyclic J-Integral to Fatigue Crack Propagation of Al 2024-T351
,”
Eng. Fract. Mech.,
40
(
2
), pp.
355
370
.10.1016/0013-7944(91)90270-B
26.
Kanninen
,
M. F.
, and
Popelar
,
C. H.
,
1985
,
Advanced Fracture Mechanics
,
Oxford University Press
,
Ney York
, Chap. 8, Sec. 8.2.
27.
Sumi
,
Y.
,
Chen
,
Y.
, and
Hayashi
,
S.
,
1996
, “
Morphological Aspects of Fatigue Crack Propagation Part I—Computational Procedure
,”
Int. J. Fract.
,
82
, pp.
205
220
.10.1007/BF00013158
28.
McClung
,
R. C.
,
Chell
,
G. G.
, and
Lee
,
Y. D.
, and
Russsell
,
D. A.
, and
Orient
,
G. E.
,
1999
, “
Development of a Practical Methodology for Elastic-Plastic and Fully Plastic Fatigue Crack Growth
,”
Southwest Research Institute, San Antonio
,
TX
, Report No. NASA/CR-1999-209428.
29.
Lee
,
E. U.
, and
Taylor
,
R.
,
2010
, “
Biaxial Fatigue of Aluminum Alloy 1100
,”
Multiaxial Fatigue & Fracture (ICMFF9)
,
Italy
, pp.
63
82
.
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