Application of Probability to Mechanical Design
111
kg - 1 for what is known
kh - corrosion neglect kh = 1
ki - surface treatment none ki = 1
k] - fretting none k] = 1
kk - shock or vibration, this is a smooth
operation kk = 1
kl - radiation none is known kl = 1
a’ e - 128,000
~=<~=o
~ = c~ = o
~; = C~ = 0
~= <~ =o
~ = C~ = 0
~ = C~ = 0
~< = +0.08<
In addition km = k~,fe from (2.2) for up to l° cycles, Km =0.85 Eq (2. 89)
0.01967 ~m
Gym -- 0.8~
-- km - 0.0231
now find Eq. (2.55)
~’e = (0.7429)128,000(0.85)
6’e = 80,828 psi
[i=n] 1/2
, 2 E C2
(2.122)
ae Cv "+vhi
i=1
[(0.08) 2 + (0.1386) 2 + (0.0231)2]~/2= 4-0.161
za, ~ =
with Table 2. I
-- = 4-0.05
Suit
A ~r
r
The
-- O" m plot can be drawn
~< = :t:0.161(80,828 psi) and ~.~t = 4-0.05(368,000)
11,250
r
0.9664 ~ (1)
am Kf 11,64~
1
Kf used both in at, O’m as Sult>200,O00
psi
The S and ~s values are derived from Fig. 2.40. The s value
S 2
2
2 [ 1 EC’~ 2 [ 1 Ec’~ 2
: + %:
.,/~ Ec
S-2 r
(2.123)