Application of Probability to Mechanical Design
91
40
~ 2o
I I
x Cast alloys
¯ Wrought alloys
=~
-~, .~xa
_
~ ~
~ ~ - -
~. zo
../L,’I~, ~x x~-~-×~= - -~ ~-v
~
X ~
~X
0
~0
20
30
40
50
~
?0
80
~
Tensile stren~h (1~ psi)
Figure 2.29 Rotating-bending fatigue strengths at 500 millions cycles of aluminum alloys. (After Grover, Gordon, and Jackson [2.15]. Courtesy of the Bureau
of Naval Weapons, U.S. Department
of the Navy). [Wrought ~ =~;
CAST = ~l
"6 40
b 20
Figure 2.30
~uglas
fir
-
_
White
oak
~
10 10
2
10 3 10 4 10 5
|0 6
10 7 10 8
Cycles to failure
Typical fatigue test data for wood. Repeated tension parallel to grain
at 900 cycles per min (see [2.40]).
Contact
km = (~m, ~m) ---- (0.7625, 0.0383)@10 ~° cycles for gear materials
(2.91)
= 1@107 cycles and ~m ~--- 0
(2.92)