This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Compound Cylinders & Gaskets”.
1. Autofrettage is beneficial for the high pressure cylinder.
a) True
b) False
View Answer
Explanation: It increases pressure capacity of the cylinder and reduces compressive stresses.
2. Autogreggate is a process of ___ stressing the cylinder.
a) Pre
b) Post
c) Over
d) None of the listed
View Answer
Explanation: It is a pre stressing phenomenon to improve pressure capacity.
3. 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
View Answer
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.
4. A compound cylinder consists of
a) 2 cylinders
b) Cylinder and a jacket
c) 2 jackets
d) At least two cylinders
View Answer
Explanation: Inner diameter of jacket increase and outer diameter of cylinder decreases when the jacket is heated.
5. 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
View Answer
Explanation: σ=P[D₃²+D₂²]/[D₃²-D₂²] where D₂=40mm and D₃=60mm.
6. 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
View Answer
Explanation: Δ=PD₂[2D₂²(D₃²-D₁²)] / Ex[(D₃²-D₂²)(D₂²-D₁²)].
7. 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
View Answer
Explanation: σ(r)=-PD₂²[D₃²/4r² – 1]/ [D₃²-D₂²].
8. 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
View Answer
Explanation: σ(t)=+PD₂²[D₃²/4r² – 1]/ [D₃²-D₂²].
9. 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]
View Answer
Explanation: σ(r)= σ(r)=-PD₂²[1-D₁²/4r² ]/ [D₂²-D₁²].
10. 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]
View Answer
Explanation: σ(r)= σ(r)=-PD₂²[1+D₁²/4r² ]/ [D₂²-D₁²].
11. 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]
View Answer
Explanation: σ(r)=-PD₁²[D₃²/4r² – 1]/ [D₃²-D₁²]. Here P=30.
12. 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]
View Answer
Explanation: σ(t)=+PD₁²[1+ D₃²/4r² ]/ [D₃²-D₁²]. Here P=30.
13. A gasket is a device to allow easy diffusion of fluids across mating surfaces of a mechanical assembly.
a) True
b) False
View Answer
Explanation: A gasket acts as a barrier between two mating surfaces to prevent fluid flow.
14. Asbestos gaskets like other non-metallic gaskets can be used only up to a temperature of 70⁰C.
a) True
b) False
View Answer
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.
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