Application of Probability to Mechanical Design
119
(s m ksi
Figure 2.43 ~, 2s Gaussian aluminum casting parameters.
46.507
minimum
Eq. (1.68)
flmin = 46,329 psi
Eq. (1.69)
~ = 3,038 psi
SO S L
SL =/tmi n -- 2.576
SL = 38,503 psi with ~ = 46,507 psi
(2.138)
Then ~e is 4,488 psi from_Eq. (2.129)
The mean line using S = 46,507 and 6e = 4488 psi is used on the failure
line with ~ra/am = 1 and N= 1 in Fig. 2.43.
1
[- O" m
O" a 1
O" m = 4093 psi -- a
a
(2.139)
~s = [O’a 2 -~-mJ a2 ]1/2 = 5788 psi
for the lower line at under 2.576 ~ Fig. 2.43 a,r _- 1 and N= 1
~mL
1 ~ffmL
~YaL 3
1 -- ¢TmL
~aL
38,50~ + 2,48~
(2.140)
(?mL = aaL = 2,332
,,.2 ]1/2
~rSL = [cr2~ L + uaLj = 3298 psi