PSI - Issue 5
Slobodanka Boljanović et al. / Procedia Structural Integrity 5 (2017) 801 – 808 Slobodanka Boljanović, Stevan Maksimović / Structural Integrity Procedia 00 (2017) 000–000
804
4
In the failure analysis, a complex geometry of cracked lug is examined by means of the corrective factor in which two corrective functions are involved, as follows:
l F a 1 1
H D
a
D Y w
D F w 2
1
,
D , 2
= −
(5)
where w and D are width and diameter of the lug, respectively, H is height of the lug head (see, Fig. 1). Under cyclic loading, the location of a hole with respect to the top of lug head can have a certain influence on the strength of the lug-pin joint, and according to Geier (1980) such an effect can be tackled through the following relationships:
1 l a
H f D
+
3
−
10
1 l F a 1
=
H D
,
(6)
1 l a
3
−
10
+
2
H D
H D
H f D
0.72 0.52 = +
0.23 −
(7)
w D −
l
=
where (see Fig. 1). As far as the through-the-thickness crack situation is taken into consideration, based on Hsu (1981) results related to the straight attachment lug, suitable polynomial expressions are herein developed for two different width diameter ratios, as follows: 2 1
5
4
3
2
a
a
a
a
a
D w
−
+
+
−
+
F
=
27.754 2
44.092 2
12.485 2
12.988 2 9.037 2 3.048;
2.0
=
(8a)
2
D
D
D
D
D
5
4
3
2
a
a
a
a
a
D w
−
+
+
−
+
F
=
8.166 2
15.303 2 3.468 2 9.294 2 7.105 2 2.605;
2.25
=
(8b)
2
D
D
D
D
D
Further, in the crack growth investigation here examined, the numerical approach is applied to simulate stress state field. Hence, by employing the MSC/NASTRAN software package in which quarter-point singular finite elements (Barsoum (1977)) are implemented, the stress distribution and the stress intensity factors are evaluated. By
Fig. 1. Geometry of the damaged attachment lug subjected to cyclic loading.
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