consent of McGraw–Hill Education.
PROBLEM 10.41
A torque of magnitude
is applied at end A of the
composite shaft shown. Knowing that the modulus of rigidity
is 77 GPa for the steel and 27 GPa for the aluminum,
determine (a) the maximum shearing stress in the steel core,
(b) the maximum shearing stress in the aluminum jacket,
(c) the angle of twist at A.
SOLUTION
Steel core:
44 9
11 11
9 9 32
11
10.027 m (0.027) 834.79 10
2 22
(77 10 )(834.79 10 ) 64.28 10 N m
cd Jc
GJ
ππ
−
−
= = = = = ×
=× ×=× ⋅
Torque carried by steel core.
Aluminum jacket:
( )
11 2 2
4 4 4 4 64
2 21
9 6 32
22
11
0.027 m, 0.036 m
22
(0.036 0.027 ) 1.80355 10 m
22
(27 10 )(1.80355 10 ) 48.70 10 N m
cd cd
J cc
GJ
ππ
−
−
= = = =
= −= − = ×
=× ×=×⋅
Torque carried by aluminum jacket.
Total torque:
1 2 11 2 2
( )/T T T GJ GJ L
ϕ
=+= +
33
33
11 2 2
4 10 35.406 10 rad/m
64.28 10 48.70 10
T
L GJ GJ
ϕ
−
×
= = = ×
+×+ ×
(a) Maximum shearing stress in steel core.
93
1 11
(77 10 )(0.027)(35.406 10 )G Gc L
ϕ
τγ
−
===××
(b) Maximum shearing stress in aluminum jacket.
93
2 22
(27 10 )(0.036)(35.406 10 )G Gc L
ϕ
τγ
−
===××
(c) Angle of twist.
33
(2.5)(35.406 10 ) 88.5 10 radLL
ϕ
ϕ
−−
== ×=×