Fatigue behaviour of BS 2L65 aluminium alloy pin - aerade

6
(d) Constant amplitude loading over a range of stress amplitudes at one tensile
mean stress°
(e) Narrow Band Random loading at two rms levels of alternating stress and one
tensile mean stress.
Specimens were tested to failure or 10 7 cycles, whichever occurred first.
Cracks were initiated by fretting between the bush and lug hole and led to
failure through the net section. A typical failure is shown in Fig 4.
The following table details the locations of the tabulated results and
associated S-N curves for each condition.
Form of Loading
Constant amplitude
~R
tt
It
t! !I
T! It
It
Mean
stress
MN/m 2
153 (95)
153 (95)
225 (14o)
153 (95)
153 (95)
153 (95)
153 (95)
225 (14o)
Prestress
gN/m 2
0
0
0
4o2 (25o)
474 (294)
0
0
0
Bushes
passivated
No
Yes
No
No
No
No
Yes
No
Table
No.
2
3
4
5
6
7
8
9
Fig No.
5
6
7
i
Fig No. of
comparison
I0
i ii i,
8 ~13
The S-N curves are based on a faired line passing as close as possible to
the log mean endurances at each stress level. All failed specimens are indicated
on these figures by a circle and dot, whilst a circle with an arrow indicates an
unbroken specimen.
In Figs 10-13 where comparisons are made of results under different condi-
tions, individual test points are omitted for clarity.
The unbushed lug data plotted in the comparison graphs, Figs 11-13, were
obtained in an earlier investigation 8 and only the faired S-N curves are
presented in this report.