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Fatigue Tem
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SUBJECT : FILE No :
Author : Date : Page :
6.0 Fatigue Analysis
Cross Section of Bracket
Max Ultimate Stress (Smax) form static case in G Factor
Max Ultimate 1G Stress (Smax) =
R = Smin/Smax = 0.10 ( From Material Data Ref [3])
AFI = =
Where:
Diameter of the Bolt (D) =
Effective Width (W) =
Bracket thickness (t) =
� t/W = 0.1
� D/W = 0.2
� Kt = 2.20 (From ESDU 09014 Figure 2)
4.8mm 2.5mm
25.00
141 32.99
4.27 MPa
1/Kt*F1*F2*F3*F4*F5*F6*F7*M*E*C
4.80mm
25.00mm
2.50mm
X
Z
Y
� Kt = 2.20 (From ESDU 09014 Figure 2)
F1(countersink effect) = 1.00 ( From Ref [6])
F2(Fastener type effect) = 1.00 ( From Ref [6])
F3( Fastener fitting condition effect) = 1.24 ( From Ref [6])
F4(Effect of preload relaxation in hybrid joint) = 1.00 ( From Ref [6])
F5(Mechanical process effect) = 1.00 ( From Ref [6])
F6(Surface treatment effect) = 0.75 ( From Ref [6])
F7(Lug and bushing effect) = 1.00 ( From Ref [6])
M (2024 T42) = 1.00 ( From Ref [6])
E =(3.175/Radius)^0.08 = 1.02 ( From Ref [6])
C (Constant) = 510 ( From Ref [6])
� AFI = 220
q = 0.60 ( From Ref [6])
p = 4.60 ( From Ref [6])
Number of cycles are calculated by following forumule
Normal Operating Case
Maximum Wing Acceleration (Nz) = ( From Ref [2])
Maximum Stress G = (Smax * Nz)
Applied Cylcels Nnormal = (from above equation)
Allowable cycles = ( From Ref [2])
d1DSG =
8.93E+05
2.88E+04
3.23E-02
136.98 MPa
32.05
( )( )
P
MAX
qsR
AFIN
×−×=
9.0/110 5
SUBJECT : FILE No :
Author : Date : Page :
Windmilling Case
Stress with amplification and SEI
Initial Descent 18G = (Smax * Q * SEI)
Cruise 17.4G = (Smax * Q * SEI)
Final Descent 5.8G = (Smax * Q * SEI)
Approach & Landing 2G = (Smax * Q * SEI)
Transient 16G = (Smax * Q * SEI)
Applied Number of cylced for Windmilling case
NInitial Descent 18G = (from above equation)
NCruise 17.4G = (from above equation)
NFinal Descent 5.8G = (from above equation)
NApproach & Landing 2G = (from above equation)
NTransient 16G = (from above equation)
Allowable Cycles (N) for 1 hr Mission Ref [1]
Initial Descent 18G = ( From Ref [1])
Cruise 17.4G = ( From Ref [1])
Final Descent 5.8G = ( From Ref [1])
Approach & Landing 2G = ( From Ref [1])
Transient 16G = ( From Ref [1])
1.56E+09
2.69E+11
8.93E+06
20000 Cylcles
25000 Cylcles
6000 Cylcles
2000 Cylcles
20 Cylcles
7.24E+06
87 MPa
27 MPa
9 MPa
83 MPa
3.38E+06
103 MPa
1N
2000
N
6000
N
20
N
25000
N
20000++++=nhrDiversioSEId
dSEI 1 Hr Diversion =
Allowable Cycles (N) for 1 hr Mission Ref [1]
Initial Descent 18G
Cruise 17.4G
Final Descent 5.8G
Approach & Landing 2G
Transient 16G
dSEI 3 Hr Diversion =
total damage (1 hour diversion mission) =
total damage (3 hour diversion mission) =
2000 Cylcles
20 Cylcles
1.88E-02
8.33E-02
5.10E-02
6000 Cylcles
9.38E-03
20000 Cylcles
93000 Cylcles
Landing andApproach Descent FinaltransientCruisedescent Initial
1N
2000
N
6000
N
20
N
25000
N
20000++++=nhrDiversioSEId
Landing andApproach Descent FinaltransientCruisedescent Initial
1N
2000
N
6000
N
20
N
93000
N
20000++++=nhrDiversioSEId
1 2 x )d(dDamage DiversionHr 1 SEI1DSGDiversionhour 1 T otal, <+=
1 )d(dDamage DiversionHr 3 SEI1DSGDiversionhour 3 Total, <+=
