The composite wall of an oven consists of three materials,two of which are of known thermal conductivity, k A = 20 W/m ⋅ K and k C = 50 W/m ⋅ K, and knownthickness, L A = 0.30 m and L C = 0.15 m . The thirdmaterial, B, which is sandwiched between materialsA and C, is of known thickness, L B = 0.15 m, butunknown thermal conductivity k B . Under steady-state operating conditions, measurementsreveal an outer surface temperature of T s , o = 20 ° C, aninner surface temperature of T s , i = 600 ° C, and an ovenair temperature of T ∞ = 800 ° C . The inside convectioncoefficient h is known to be 25 W/m 2 ⋅ K . What is thevalue of k B ?
The composite wall of an oven consists of three materials,two of which are of known thermal conductivity, k A = 20 W/m ⋅ K and k C = 50 W/m ⋅ K, and knownthickness, L A = 0.30 m and L C = 0.15 m . The thirdmaterial, B, which is sandwiched between materialsA and C, is of known thickness, L B = 0.15 m, butunknown thermal conductivity k B . Under steady-state operating conditions, measurementsreveal an outer surface temperature of T s , o = 20 ° C, aninner surface temperature of T s , i = 600 ° C, and an ovenair temperature of T ∞ = 800 ° C . The inside convectioncoefficient h is known to be 25 W/m 2 ⋅ K . What is thevalue of k B ?
Solution Summary: The author calculates the value of k B based on thermal circuit diagrams.
The composite wall of an oven consists of three materials,two of which are of known thermal conductivity,
k
A
=
20
W/m
⋅
K
and
k
C
=
50
W/m
⋅
K,
and knownthickness,
L
A
=
0.30
m
and
L
C
=
0.15
m
.
The thirdmaterial, B, which is sandwiched between materialsA and C, is of known thickness,
L
B
=
0.15
m,
butunknown thermal conductivity
k
B
.
Under steady-state operating conditions, measurementsreveal an outer surface temperature of
T
s
,
o
=
20
°
C,
aninner surface temperature of
T
s
,
i
=
600
°
C,
and an ovenair temperature of
T
∞
=
800
°
C
.
The inside convectioncoefficient h is known to be
25
W/m
2
⋅
K
.
What is thevalue of
k
B
?
PROBLEM 3.23
3.23 Under normal operating condi-
tions a motor exerts a torque of
magnitude TF at F. The shafts
are made of a steel for which
the allowable shearing stress is
82 MPa and have diameters of
dCDE=24 mm and dFGH = 20
mm. Knowing that rp = 165
mm and rg114 mm, deter-
mine the largest torque TF
which may be exerted at F.
TF
F
rG-
rp
B
CH
TE
E
1. (16%) (a) If a ductile material fails under pure torsion, please explain the failure
mode and describe the observed plane of failure.
(b) Suppose a prismatic beam is subjected to equal and opposite couples as shown
in Fig. 1. Please sketch the deformation and the stress distribution of the cross
section.
M
M
Fig. 1
(c) Describe the definition of the neutral axis.
(d) Describe the definition of the modular ratio.
using the theorem of three moments, find all the moments, I only need concise calculations with minimal explanations. The correct answers are provided at the bottom
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