Problems 1-1 through 1-6 are for student research. No standard solutions are provided.
t t t t t t t t t t t t
1-7 From Fig. 1-2, cost of grinding to 0.0005 in is 270%. Cost of turning to 0.003 in is
t t t t t t t t t t t t t t t t t t t
60%.
t
Relative cost of grinding vs. turning = 270/60 = 4.5 times Ans.
t t t t t t t t t t
1-8 CA = CB,
t t
10 + 0.8 P = 60 + 0.8 P 0.005 P2
t t t t t t t t t t t t
P2 = 50/0.005
t t t P = 100 parts Ans.
t t t t
1-9 Max. load = 1.10 P
t t t t
Min. area = (0.95)2A
t t t t
Min. strength = 0.85 S
t t t t t
To offset the absolute uncertainties, the design factor, from Eq. (1-1) should be
t t t t t t t t t t t t
1.10
nd 1.43 Ans.
0.850.95
t
t 2
1-10 (a) X1 + X2:
t t t
x1 x2 X1 e1 X2 e2
t
t
t
t
t
t
t
t t
t
t
error e x1 x2X1 X2 t t t t t t t t t t t t t t
e1 e2 t
t
t Ans.
(b) X1 X2: t t
x1 x2 X1 e1 X2 e2
t t t t t t t t t t t t t
e x1 x2X1 X2 e1 e2
t t t t t t t t t t t t t t t t t Ans.
(c) X1 X2: t
x1x2 X1 e1X2 e2 t t t t t t t t t t t
e x1x2 X1 X2 X1e2 X2e1 e1e2
t t
t t
t
t
t
t
t
t
t t
t
t
t
X e Xe XX e2 Ans.
e1
t t t
t t
t
2
t
1 2 2 1 1 t t t t t t
X X
1 2
t t
t
Chapter 1 Solutions - Rev. B, Page 1/6
t t t t t t t
, (d) X1/X2:
x1 X 1 e1 X X1
1 e1 1
t
t t t t t
t t
t t
X e
t
x X 1 e X t t t t t t
2 2 2 2 2 2 t t
1
e e 1 e X e t e t e e t t t t t t t t t
1 2
then
1 1 1 1 2
2 t t 1 1 1t 2 t 1 t t t t t tt t t t t t t t t t t t t t
t t t t t t t
t t t
X 2 X 2 1 e2 X 2
t
X 1 t
X 2 X 1 X2 t
t
t t
t
t
t
t
t
x1 X1
Thus, e X1 e Ans.
t
2
t t t
t
t
e1 t
t
X X
t
x X X
t
2 1 2
t
2 2 t t
1-11 (a) x1 = 7 = 2.645 751 311 1
t t t t t t
X1 = 2.64 t(3 correct digits)
t t t
x2 = 8 = 2.828 427 124 7
t t t t t t
X2 = 2.82 t(3 correct digits)
t t t
x1 + x2 = 5.474 178 435 8
t t t t t t t
e1 = x1 X1 = 0.005 751 311 1
t t t t t t t t t
e2 = x2 X2 = 0.008 427 124 7
t t t t t t t t t
e = e1 + e2 = 0.014 178 435 8
t t t t t t t t t
Sum = x1 + x2 = X1 + X2 + e
t t t t t t t t t t t
= 2.64 + 2.82 + 0.014 178 435 8 = 5.474 178 435 8
t t t t t t t t t t t t t Checks
(b) X1 = 2.65, X2 = 2.83 (3 digit significant numbers)
t t t t t t t t t
e1 = x1 X1 = 0.004 248 688 9
t t t t t t t t t t
e2 = x2 X2 = 0.001 572 875 3
t t t t t t t t t t
e = e1 + e2 = 0.005 821 564 2
t t t t t t t t t t
Sum = x1 + x2 = X1 + X2 + e
t t t t t t t t t t t
= 2.65 +2.83 0.001 572 875 3 = 5.474 178 435 8
t t t t t t t t t t t t Checks
S 161000 25 103 t
1-12
t
t d 0.799 in t t t Ans.
n d 3
t 2.5
7
Table A-17: t d= t t
t
in Ans.
8
25 103
n S 3.29
t
Factor of safety:t t t t t t Ans.
161000 t
7
3
t t t
1-13 Eq. (1-5):
t t t R =Ri = 0.98(0.96)0.94 = 0.88
t t
t t
t t t
i1
Overall reliability = 88 percent
t t t t Ans.
Chapter 1 Solutions - Rev. B, Page 2/6
t t t t t t t
,Chapter 1 Solutions - Rev. B, Page 3/6
t t t t t t t
, 1-14 a = 1.500 0.001 in
t t t t t
b = 2.000 0.003 in
t t t t t
c = 3.000 0.004 in
t t t t t
d = 6.520 0.010 in
t t t t t
(a) w d a b c = 6.520 1.5 2 3 = 0.020 in t t t t t t t t t t t t t t t t t t t
tw tall = 0.001 + 0.003 + 0.004 +0.010 = 0.018
t
t
t
t t t t t t t t
w = 0.020 0.018 in
t Ans.
t t t t
(b) From part (a), wmin = 0.002 in. Thus, must add 0.008 in to d . Therefore,
t t t t t t t t t t t t t t t t
d = 6.520 + 0.008 = 6.528 in
t t t t t t t Ans.
1-15 V = xyz, and x = a a, y = b b, z = c c,
t t t t t t t t t t t t t t t t t t t t t t t
V abc
t t
V a ab bc c
t t t t t t t t
abc bca acb abc abc bca cab abc
t t t t t t t t t t t t t t t
The higher order terms in are negligible. Thus,
t t t t t t t t
V bcaacbabc
t t t t t t
V bca acb abc a b c a b c
and,
t t t t t t t t t t t t
Ans. t t t t t t t
V abc a b c a b c
For the numerical values given, V 1.5001.8753.000 8.4375 in3
t t t t t t t t t t
V 0.002 0.003 0.004
0.00427 V 0.004278.4375 0.036 in3
t t t t
t t t t t t t t t t
V 1.500 1.875 3.000
V = 8.438 0.036 in3
t t t t t Ans.
Chapter 1 Solutions - Rev. B, Page 4/6
t t t t t t t