Download - ข้อสอบสามัญเครื่องกล Main Group 2/2547
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10 5
THERMODYNAMICS 1 2 , FLUID MECHANICS 3 4 ,
DYNAMICS 5 6 , STRENGTH OF MATERIAL 7 8
MANUFACTURING 9 10
THERMODYNAMICS
1. (20 )1.1
300
C ?
300C 8581 kPa 8581 kPa
1.2 1 40OC 2,000 kPa 2,000 kPa
1 q = h2-h1 1 h1 = 169.30 kJ/kg 167.54kJ/kg 2 212.42 OC , h2 = 2799.51 kJ/kg q = 2799.51-169.30 = 2630.21 kJ/kg 2799.51-167.54 = 2631.97 kJ/kg
1.3 1 m3/s 100 kPa 20OC 20,000 kPa 25,000 kW ?
W =
V P
V = 1 m3/s P = 20,000-100 = 19,900 kPa
W = 1x 19,900 = 19,900 kW = 19,900/25,000 = 0.796=79.6%
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W =
m (vP + CT) =
V P
mCT
W = 25,000 kW,
V P=19,900 kW, C =4.186 kJ/kg.K,
m = 1/0.001002 =998 kg/s
25,000 = 19,900998x4.186T
T = 5,100/ (1000x4.186) =1.22oC = 20+1.22 =21.22 oC
2. (20 )2.1 30 OC 1 m3
?
30OC 4.246 kPa2.2 1 (1st Law of Thermodynamics)
?
100 W 60 W 40 W 60 W 100 W 100 W
2.3 H2O 100OC 10,000 kPa 1 /
500 OC 10,000 kPa
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1
Q =
m[he hi]
hi = 426.48 kJ/kg 419.02 kJ/kg he = 3373.63 kJ/kg,
m= 1 kg/s
Q = 1 x (3373.63426.48) = 2947.15 kW 2954.61 kW
FLUID MECHANICS
3. 40 20 2 / 100 0.15
0.2
D = 0.4
2
1
1 0.4D 2 0.2D 1 2V /
1 100p kPag 2 101.3p kPa 101.3 101.3 0 kPag 0.15
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CV
x
y xR
yR
B Scv cs
F F F V d V V dAt
vv v v v v v
cv cs
d V dAt
vv
= 0
1. 2. 3.
4. , 0
xBx F
2 t
1 1 2 2 0CS
V dA V A V A 2 2
1 12 1 1 2 2
2 2
0.4(2) 8
0.2
A DV V V
A D /
x xScs
F u V dA
1 1 2 2 2 2 2 1 1 1( )x xa CV a CV g g xp A p A p A p A R V V A V V A
2 22 2 1 1 2 2 1 1 x g g R V A V A p A p A
2 2 2 2 23 3 310 8 0.2 10 2 0.4 0 100 10 0.44 4 4
15079.63
y Sy Bycs
F F V dA
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y y y y y
0y ya CV a CV y
p A p A R W g
y R W g ( )W 0
310 9.81 0.15 1471.50yR
15079.63 1471.50 R i j R
15079.63 1471.50 R i j Ans
4. 800 / 3 6.8
x 10-6 2/ 76
1.1 / commercial steel 300
1CV2CV
3 1 2
0.76D commercial steel 1.1V /3300 10L 66.8 10 2/ 800
/ 3
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2 21 1 2 2
1 1 2 22 2 T
p V p V gz gz h
l
2 2 2
,2 2 2T m
eL L V V V h f h K f D D
l l
2
( )2
shaft shear other
cv cs
Q W W W p V e d u gz V d
dt dt dt dt t
r r
2
2
Ve u gz
1 ( 1)CV
1.
2.22
1 21 2
2 2
V V
3. 1 2z z4. 5.
6.
2
2TL V
h fD
l
2 2(0.76) 0.4544 4
A D
m2
,D f f Re e D5
6
1.1 0.761.229 10
6.8 10D
VD VDRe
commercial steel 0.046e .
35
3
0.046 106.05 10
760 10
e
D
DRe e D f Moody 0.0175f
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2 3 2300 10 1.10.0175 4179.28
2 0.76 2TL V
h fD
l 2/2 Ans
2
1 22
L V p p f
D
( 2 ( 2)CV
1.22
311 3
2 2
VV
2. 1 3z z
3. 4. 1p ( 3p )
2p
5. 100 % 2 1( ) 0Q
m u udt
&
2
311 2( ) ( )
2
pW p L V m VA p p VA f
dt D
&
2 3 2(.76) 300 10 1.1800(1.1) (0.0175)
4 0.76 2
W
dt
31668.4 10
1668.4 Ans
DYNAMICS
5. 1,600
200 500
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uox 200
km
hr:= uoy 0
m
s:=
x 50 0m:= ; t xuox:=
t = 9
9 y uoy t1
2g t
2+:=
h 1600m y:= ; h 1 203m=
6. 60 10 2 100
m2 10kg:= 60deg:=
Tm 100N:=
Tm cos 60deg( ) T1 cos 60deg( ) a m2
T1
m2 g Tm sin ( )
sin ( ):= T1 13.237N=
Tm sin 60deg( ) T1 sin 60deg( )+ m2 g
aTm cos 60 deg( ) T1 cos 60 deg( )
m2
:=
a 4.338 ms
2
=
8
60o 60o
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I
Ymax
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STRENGTH OF MATERIAL
7. (20 )1.1 (section modulus)
m m 3
z =
1.2 (simple torsion theory)
1. 2. 3. 4. 5. 6.
7.
1.3 Complementary shear stresses 2
1.4 Principal plane principal stresses 2 2
principal planes principalstresses
1.5 (modulus of elasticity) (shear modulus) (Poissons ratio)
(modulus of elasticity) (shear modulus) (Poissons ratio)
E= 2G(1+)
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1.6 (strain energy) proof strain energy proof strain energy
1.7 Flexible rigidity EI
1.8
equivalent section
1.9 slide complementary shear stresses
1.10 (Euler)
8. 2.7 mm 2.5 mm 62 MPa, () () 200 86 GPa .
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MANUFACTURING 9. Machining
machining
1. machining
1.1 - (Turning) Cutting Tool
- (Boring)
- (Drilling) - (Threading / Tapping)
Bolt Nut
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- (Facing) - (Shaping / planning) - (Broaching) - ( Sawing) - (Grinding / Lapping)
1.2 - Ultrasonic Machining
- - Electro Chemical Machining (ECM) - Electric Discharge Machine (EDM) - Wire Cut
2. Machining
Machining
Machine (Forging) Machine
Machining Machining Machining
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10. Compressor Supplier Compressor 500
1.
1) 500 25 20 5
1.1
1.2
1.3 Compressor - Nut Screw
2)
2.1 5 Safety QC Circle
2.2 Top Management PDCA
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3) QC , 7 Tools
2. ISO 9002 QMR
1. ISO-9002
2. ISO-9002
ISO-9002 15-20 3. ISO-90024. ISO-9002 1.5 5. 6.
7. QMR ISO-9002
8. (QM), (QP),
(WI), (FM)
9. QM, QP, WI,FM.
10. (Internal Audit)
11. QMR
12. ISO-9002
( Corrective Action Requirement)
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CAR
13. QMR CAR
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14. ISO-9002
15. 1-2 QMR
16. ISO-9002
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