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PROBLEM (9.7) A rectangular shaft of depth a and width b is subjected to an axial tensile load P
and a torque T, as shown in Fig. P9.7. What is the largest permissible value of T if the allowable tensile
stress in the shaft is σ all ?
Given:
a = 3 in.,
b = 2 in.,
P = 30 kips,
σ all
= 20 ksi
SOLUTION
P
30
=
= 5 ksi
A 3× 2
From Table 5.1, with a b = 1.5 :
T
T
τ=
=
= 0.3608T
2
α ab (0.23)(3)(2) 2
σ=
σ1 =
σ
(T in kip ⋅ in.)
σ
+ ( ) 2 + τ 2 = σ all
2
2
= 2.5 + (2.5) 2 + (0.3608Tall ) 2 = 20
or
Tall = 48 kip ⋅ in.
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