Cylinders and Pressure Vessels and Design of IC Engine Components
1. A cylinder is considered thin when the ratio of inner diameter to wall thickness is more than 5.
A. True
B. False
.
Answer: B
Explanation: A cylinder is considered thin when the ratio of inner diameter to wall thickness is more than 15.
2. Tangential stress in a cylinder is given by [symbols have their usual meanings].
A. PD/2t
B. 2PD/t
C. PD/4t
D. 4PD/t
.
Answer: A
Explanation: Considering equilibrium in half portion of cylinder of unit length, DP=2σt.
3. Longitudinal stress in a cylinder is given by [symbols have their usual meanings].
A. PD/2t
B. 2PD/t
C. PD/4t
D. 4PD/t
.
Answer: C
Explanation: Considering equilibrium PxπD²/4=σxπDt.
4. A seamless cylinder of storage capacity of 0.03mᵌis subjected to an internal pressure of 21MPa. The ultimate strength of material of cylinder is 350N/mm².Determine the length of the cylinder if it is twice the diameter of the cylinder.
A. 540mm
B. 270mm
C. 400mm
D. 350mm
.
Answer: A
Explanation: 0.03=πd²L/4 and L=2d.
5. A seamless cylinder of storage capacity of 0.03mᵌis subjected to an internal pressure of 21MPa. The ultimate strength of material of cylinder is 350N/mm².Determine the thickness of the cylinder if it is twice the diameter of the cylinder.
A. 12mm
B. 4mm
C. 8mm
D. 16mm
.
Answer: C
Explanation: t=PD/2σ.
6. Cylinder having inner diameter to wall thickness ratio less than 15 are
A. Thin cylinders
B. Thick Cylinders
C. Moderate cylinders
D. None of the listed
.
Answer: B
Explanation: Smaller dia to thickness ratio implies more thickness and hence these are classified under thick cylinder.
7. Lame’s equation used to find the thickness of the cylinder is based on maximum strain failure.
A. True
B. False
.
Answer: B
Explanation: It is based on maximum principal stress theory.
8. Lame’s equation is generally used for ductile materials.
A. True
B. False
.
Answer: B
Explanation: Lame’s equation is used to determine thickness of the brittle as it used principal stress theory.
9. The piston rod of a hydraulic cylinder exerts an operating force of 10kN. The allowable stress in the cylinder is 45N/mm². Calculate the thickness of the cylinder using Lame’s equation. Diameter of the cylinder is 40mm and pressure in cylinder is 10MPa.
A. 2.05mm
B. 4.2mm
C. 5.07mm
D. None of the listed
.
Answer: C
Explanation: t=D/2[√[σ+ P /σ-P] -1 ].
10. The piston rod of a hydraulic cylinder exerts an operating force of 10kN. The allowable stress in the cylinder is 70N/mm². Calculate the thickness of the cylinder using Clavarinoe’s equation. Diameter of the cylinder is 240mm.μ=0.3 and pressure in cylinder is 15MPa.
A. 35mm
B. 30mm
C. 27mm
D. None of the listed
.
Answer: C
Explanation: t=D/2[√[σ+(1-2μ) P /σ-(1+μ)P] -1 ].
11. Autofrettage is beneficial for the high pressure cylinder.
A. True
B. False
.
Answer: A
Explanation: It increases pressure capacity of the cylinder and reduces compressive stresses.
12. Autogreggate is a process of ___ stressing the cylinder.
A. Pre
B. Post
C. Over
D. None of the listed
.
Answer: A
Explanation: It is a pre stressing phenomenon to improve pressure capacity.
13. Can we pre-stress the cylinder by subjecting cylindrical portion near inner diameter in plastic range and outer diameter is still in the elastic range.
A. True
B. False
.
Answer: A
Explanation: On releasing the pressure, outer portion contracts exerting pressure on the inner portion which has undergone permanent deformation. This induces residual compressive stresses at the inner surface.
14. A compound cylinder consists of
A. 2 cylinders
B. Cylinder and a jacket
C. 2 jackets
D. At least two cylinders
.
Answer: B
Explanation: Inner diameter of jacket increase and outer diameter of cylinder decreases when the jacket is heated.
15. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². Calculate the shrinkage pressure.
A. 5.88N/mm²
B. 2.28N/mm²
C. 4.56N/mm²
D. 3.66N/mm²
.
Answer: B
Explanation: σ=P[D₃²+D₂²]/[D₃²-D₂²] where D₂=40mm and D₃=60mm.
16. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². Calculate the interference [E=210kN/mm²].
A. 2.8mm
B. 4.6mm
C. 5.4mm
D. 4.8mm
.
Answer: A
Explanation: Δ=PD₂[2D₂²(D₃²-D₁²)] / Ex[(D₃²-D₂²)(D₂²-D₁²)].
17. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². Calculate the radial stresses due to shrink shift in jacket.
A. +2.56[(45/r) ² – 1]
B. 1.824[(45/r) ² – 1]
C. -1.824[(45/r) ² – 1]
D. None of the listed
.
Answer: C
Explanation: σ(r)=-PD₂²[D₃²/4r² – 1]/ [D₃²-D₂²].
18. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². Calculate the tangential stresses due to shrink shift in jacket.
A. +2.56[(45/r) ² – 1]
B. 1.824[(45/r) ² – 1]
C. -1.824[(45/r) ² – 1]
D. None of the listed
.
Answer: B
Explanation: σ(t)=+PD₂²[D₃²/4r² – 1]/ [D₃²-D₂²].
19. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². Calculate the radial stress due to shrink shift in inner tube.
A. +3.04[1-(15/r) ²]
B. -3.04[1-(15/r) ²]
C. -3.04[1-(10/r) ²]
D. +3.04[1-(10/r) ²]
.
Answer: B
Explanation: σ(r)= σ(r)=-PD₂²[1-D₁²/4r² ]/ [D₂²-D₁²].
20. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². Calculate the tangential stress due to shrink shift in inner tube.
A. +3.04[1+ (15/r) ²]
B. -3.04[1+ (15/r) ²]
C. -3.04[1-(10/r) ²]
D. +3.04[1-(10/r) ²]
.
Answer: B
Explanation: σ(r)= σ(r)=-PD₂²[1+D₁²/4r² ]/ [D₂²-D₁²].
21. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². In service the cylinder is further subjected to an internal pressure of 25MPa. Calculate the radial stress in compound cylinder.
A. -3.75[(45/r) ² – 1]
B. +3.75[(45/r) ² – 1]
C. -3.75[(45/r) ² -+1]
D. +3.75[(45/r) ² +1]
.
Answer: A
Explanation: σ(r)=-PD₁²[D₃²/4r² – 1]/ [D₃²-D₁²]. Here P=30.
22. A high pressure cylinder consists of a steel tube with inner and outer diameters 30 and 60mm respectively. It is jacketed by an outer steel tube, having an outer diameter of 90mm. Maximum principal stress induced is 80N/mm². In service the cylinder is further subjected to an internal pressure of 25MPa. Calculate the tangential stress in compound cylinder.
A. -6.75[(45/r) ² + 1]
B. +3.75[(45/r) ² +1]
C. -3.75[(45/r) ² +1]
D. -3.75[(45/r) ² -1]
.
Answer: B
Explanation: σ(t)=+PD₁²[1+ D₃²/4r² ]/ [D₃²-D₁²]. Here P=30.
23. A gasket is a device to allow easy diffusion of fluids across mating surfaces of a mechanical assembly.
A. True
B. False
.
Answer: B
Explanation: A gasket acts as a barrier between two mating surfaces to prevent fluid flow.
24. Asbestos gaskets like other non-metallic gaskets can be used only up to a temperature of 70⁰C.
A. True
B. False
.
Answer: B
Explanation: Asbestos can be used upto a temperature of 250⁰C while all other non-metallic gaskets can be used only upto a temperature of 70⁰C.
25. Compression Ratio in diesel engine is lesser than that in Spark Ignition engine.
A. True
B. No
C. They are equal
D. Doesn’t matter
.
Answer: B
Explanation: In diesel engine, there is no spark to ignite, charge is compressed to greater extent to support self-ignition.
26. Petrol engine are more economical than diesel engine.
A. True
B. False
.
Answer: B
Explanation: Diesel engine have better thermal efficiency and hence are more economical.
27. There are ____ types of liners.
A. 1
B. 2
C. 3
D. 4
.
Answer: B
Explanation: Dry liners and wet liners.
28. If no re boring allowance is to be given, then thickness of cylinder wall is max pressure is 3.5N/mm², bore diameter=200mm and permissible tensile stress is 40N/mm².
A. 7mm
B. 8mm
C. 9mm
D. 10mm
.
Answer: C
Explanation: t=pD/2σ=8.75mm.
29. If diameter of cylinder of bore is 120mm, then thickness of the cylinder will be
A. Information not sufficient
B. 7mm
C. 12mm
D. 6mm
.
Answer: B
Explanation: t=0.045D + 1.6.
30. If diameter of cylinder bore is 120mm, then thickness of dry liner will be
A. 2.2mm
B. 3.6mm
C. 4.8mm
D. 6mm
.
Answer: B
Explanation: t= 0.03D to 0.035D.
31. If diameter of cylinder bore is 120mm, then thickness of water jacket wall will be
A. 4.26mm
B. 5.25mm
C. 2.56mm
D. All of the listed
.
Answer: D
Explanation: p=t/3 to 3t/4, where t= thickness of cylinder wall=7mm.
32. If diameter of cylinder bore is 120mm, then thickness of water cylinder flange will be
A. 8.8mm
B. 10.2mm
C. 7.8mm
D. 12mm
.
Answer: A
Explanation: q=1.2t to 1.4t.
33. If nominal diameter of bolt used is 20mm, then find the radial distance between outer diameter of flange and pitch circle diameter of studs.
A. 24mm
B. 28mm
C. 32mm
D. 36mm
.
Answer: B
Explanation: r=d+6 to 1.5d i.e. 26mm to 30mm.
34. The circumferential hoop stress and longitudinal stress are both shear stress.
A. True
B. False
.
Answer: B
Explanation: They both are tensile stress.
35. The circumferential hoop stress and longitudinal stress act in same direction and hence are straight away added.
A. True
B. False
.
Answer: B
Explanation: They both act perpendicularly to each other and thus net stress in these directions is reduced.
