_______________________________________________________________________
PROBLEM (9.4) Determine the largest value of the axial load P that can be carried by the stepped
steel shaft shown in Fig. P9.4 for allowable bending and shear shear stresses all
σ
and all
τ
, respectively.
Given: all
σ
= 100 MPa , all
τ
= 60 MPa, T = 0.01P N
⋅
m.
SOLUTION
22
(58 50 ) 216
4
CD
Am
2
m
π
π
=−=
44 6
(58 50 ) 0.158 10
32
CD
Jm
4
m
π
π
=−=×
46
(50 ) 0.195 10
32
AB
Jm
4
m
π
π
==×
Since
J, the critical section is in CD. Thus,
AB CD
J>
64630
216 10
xPP
σ
π
π
−
==
×
3
6
0.01 (29 10 )
0.158 10
P
τπ
−
−
×
=− ×
1835P
π
=−
CD
CD
Tc
xP
σ
=
CD
A
J
τ
=
Equation (9.1):
22
14630 4630 1835
()(
22
PP
σπππ
−
=+ + )
P
2315 2954 5269PPP
π
ππ
==+
max 2954P
τπ
=
We have
65269
100 10 , 59.6
PPkN
π
×= =
62954
60 10 , 63.8
PPkN
π
×= =
Thus,
kNPall 6.59=
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