_______________________________________________________________________
PROBLEM (9.8) A shaft with an a x b rectangular cross section is acted upon by an axial tensile load
P and a torque T (Fig. P9.7). Determine the largest permissible value of P if the allowable tensile
stress in the member is limited to all
σ
.
Given: a = 100 mm, b = 50 mm, T = 5 kN
⋅
m, all
σ
= 120 MPa
SOLUTION
By Table 5.1, with 2:ab=
3
22
5(10 ) 81.3
(0.246)(0.1)(0.05)
T
M
Pa
ab
τα
== =
200 (
(0.1)(0.05)
PPMPa P
σ
== in )
M
N
Hence
22
1()
22 all
σσ
σ
τσ
=+ + =
22
100 (100 ) (81.3) 120PP=+ + =
22
(120 100 ) 10,000 6,609.7PP−= +
22
14,400 24,000 10,000 10,000 6,609.7PP P−+ = +
or
0.3246 325
all
PMN== kN
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