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PROBLEM (9.82) Referring to Fig. P9.77, design a solid steel shaft ( y
= 60 MPa) subjected
to loads of R = 600 N, Q = 200 N, and P = 0. Apply the maximum shear stres theory using a
factor of safety
n= 1.2.
SOLUTION
At the fixed end:
200 2 400
y
Nm=×= ⋅
600 2 1.2
z
kN m=− × =− ⋅
600 1.5 900TNm=×= ⋅
A load-diagram is shown in Fig. S9.82a.
From the moment and torque diagrams we observe that the critical point
is just to the right of A.
Thus,
222 2 2 2
400 1200 900
yz
MMT++= + +
1552 Nm=⋅
Since
60 50
1.2
all
Pa
σ
==
Equation (9.30) is thus
3
36
16(1552) 54.1 10
(50 10 )
d
π
==×
×54.1 mm
Use a
55-mm diameter shaft.
Q
y
z
900 N
400 N⋅m
-1.2 kN⋅m
2 m
y
T
z
T
Figure S9.82
d