The energy-based lifing method is based on the theory that the cumulative energy in all hysteresis loops of a specimens' lifetime is equal to the energy in a monotonic tension test. Based on this theory, fatigue life can be calculated by dividing monotonic tensile energy by a hysteresis energy model, which is a function of stress amplitude. Due to variations in the empirically measured hysteresis loops and monotonic fracture area, fatigue life prediction with the energy-based method shows some variation as well. In order to account for these variations, a robust design optimization technique is employed. The robust optimization procedure uses an interval uncertainty technique, eliminating the need to know an exact probability density function for the uncertain parameters. The robust optimization framework ensures that the difference between the predicted lifetime at a given stress amplitude and the corresponding experimental fatigue data point is minimized and within a specified tolerance range while accounting for variations in hysteresis loop energy and fracture diameter measurements. Accounting for these experimental variations will boost confidence in the energy-based fatigue life prediction method despite a limited number of test specimens.

References

References
1.
Stowell
,
E.
,
1966
, “
A Study of the Energy Criterion for Fatigue
,”
Nucl. Eng. Des.
,
3
, pp.
32
40
.10.1016/0029-5493(66)90146-4
2.
Scott-Emuakpor
,
O.
,
Shen
,
M.-H. H.
,
George
,
T.
, and
Cross
,
C.
,
2008
, “
An Energy-Based Uniaxial Fatigue Life Prediction Method for Commonly Used Gas Turbine Engines Materials
,”
ASME J. Eng. Gas Turbines Power
,
130
, pp.
1
15
.10.1115/1.2943152
3.
Scott-Emuakpor
,
O.
,
Shen
,
M.-H. H.
,
George
,
T.
, and
Cross
,
C.
,
2010
, “
Multi-Axial Fatigue-Life Prediction Via a Strain-Energy Method
,”
AIAA J.
,
48
(
1
), pp.
63
72
.10.2514/1.39296
4.
Scott-Emuakpor
,
O.
,
George
,
T.
,
Cross
,
C.
, and
Shen
,
M.-H. H.
,
2010
, “
Hysteresis Loop Representation for Strain Energy Calculation and Fatigue Assessment
,”
J. Strain Anal. Eng. Des.
,
45
(
4
), pp.
275
282
.10.1243/03093247JSA602
5.
Wertz
,
J.
,
Letcher
,
T.
,
Shen
,
M.-H. H.
,
Scott-Emuakpor
,
O.
,
George
,
T.
, and
Cross
,
C.
,
2012
, “
An Energy-Based Axial Isothermal-Mechanical Fatigue Lifing Method
,”
ASME
Paper No. GT2012-68889.10.1115/GT2012-68889
6.
Gunawan
,
G.
, and
Azarm
,
S.
,
2004
, “
Non-Gradient Based Parameter Sensitivity Estimation for Single Objective Robust Design Optimization
,”
ASME J. Mech. Des.
,
126
, pp.
395
402
.10.1115/1.1711821
7.
American Society of Test and Materials
,
2007
, “
ASTM E466: Standard Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials
,”
Book of Standards
, Vol. 03.01,
ASTM
,
West Conshohocken, PA
.
8.
Aerospace Material Specifications
,
2008
, “
SAE AMS 2772-E: Heat Treatment of Aluminum Alloy Raw Materials
,” SAE, Warrendale, PA.
9.
American Society for Test and Materials
,
2008
, “
ASTM B211-03-M: Standard Specification for Aluminum and Aluminum-Alloy Bar Rod and Wire
,”
Book of Standards
, Vol. 02.02,
ASTM
,
West Conshohocken, PA
.
10.
American Society for Test and Materials
,
2008
, “
ASTM E8/E8M-08: Standard Test Methods for Tension Testing of Metallic Materials
,”
Book of Standards
, Vol. 03.01,
ASTM
,
West Conshohocken, PA
.
11.
MTS
, 1998,
TestStar IIs Software Manual
, MTS Systems Corp.,
Eden Prairie
,
MN
.
12.
The MathWorks Inc.,
2011
, MATLAB Version2011a, MathWorks, Natick, MA.
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