Machine Design Multiple Choice Questions on “Compound Cylinders & Gaskets”.
1. Autofrettage is beneficial for the high pressure cylinder.
a) True
b) False
Answer: a
Clarification: 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
Answer: a
Clarification: 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
Answer: a
Clarification: 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
Answer: b
Clarification: 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
Answer: b
Clarification: 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
Answer: a
Clarification: 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
Answer: c
Clarification: 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
Answer: b
Clarification: 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]
Answer: b
Clarification: 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]