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Question 1
ప్రశ్న 1
Which statement best describes the thin-wall idealization used for a cylindrical pressure vessel?
Explanation:
Thin-cylinder theory requires the wall thickness to be small compared with the vessel diameter or radius. Under this condition, the circumferential and longitudinal membrane stresses can be treated as approximately uniform through the thickness. The radial stress changes from approximately the internal pressure at the inner surface to the external pressure at the outer surface, but its magnitude is usually small compared with the membrane stresses when the radius-to-thickness ratio is large. This permits the wall to be analysed mainly as a membrane rather than by thick-cylinder stress equations. Therefore Option A is correct.
వివరణ:
Question 2
ప్రశ్న 2
For a thin cylindrical vessel of mean diameter d and wall thickness t subjected to internal pressure p, which expression gives the circumferential or hoop stress?
Explanation:
Hoop stress is obtained by considering equilibrium of a longitudinally cut half-cylinder. Internal pressure acting over the projected diameter produces a separating force proportional to pd per unit vessel length. This force is resisted by tensile forces in the two cut wall sections, each having thickness t. Equilibrium gives 2σh t = pd, and therefore σh = pd/(2t). Hence Option A is correct.
వివరణ:
Question 3
ప్రశ్న 3
For a thin closed-end cylindrical vessel subjected only to internal pressure p, which expression gives the longitudinal membrane stress using mean diameter d and wall thickness t?
Explanation:
Longitudinal stress is obtained by cutting the closed cylinder transversely and balancing the pressure force on the end closure. The pressure force is approximately pπd²/4 under the thin-wall diameter approximation. The resisting metal area around the circumference is approximately πdt. Equating the axial pressure force to σlπdt gives σl = pd/(4t). Therefore Option B is correct.
వివరణ:
Question 4
ప్రశ్న 4
For a thin closed-end cylindrical pressure vessel subjected only to internal pressure, what is the relationship between hoop stress σh and longitudinal stress σl?
Explanation:
The thin-cylinder hoop stress is σh = pd/(2t). The longitudinal pressure stress in a closed-end cylinder is σl = pd/(4t). Dividing the first relation by the second gives σh/σl = 2. Thus hoop stress is twice the longitudinal stress under internal pressure alone. Therefore Option C is correct.
వివరణ:
Question 5
ప్రశ్న 5
A thin cylindrical tube is open at both ends and is pressurized internally without any end caps or externally applied axial load. Ignoring local end effects, which membrane stresses are produced by the pressure?
Explanation:
Internal pressure acting on the curved wall still tends to split the cylinder along a longitudinal plane. The tube therefore develops the usual hoop membrane stress approximately equal to pd/(2t). Without closed ends, however, pressure does not act on an end closure to create a net axial separating force in the shell. Consequently there is no longitudinal membrane stress due solely to pressure in the ideal open-ended tube. Therefore Option B is correct.
వివరణ:
Question 6
ప్రశ్న 6
A thin closed-end cylinder has mean diameter 1000 mm, wall thickness 10 mm and internal pressure 2 MPa. What are the hoop and longitudinal stresses?
Explanation:
The hoop stress is σh = pd/(2t). Substitution gives σh = 2 × 1000/(2 × 10) = 100 MPa. The longitudinal stress is σl = pd/(4t) = 50 MPa. As expected for a closed thin cylinder, the hoop stress is twice the longitudinal stress. Therefore Option B is correct.
వివరణ:
Question 7
ప్రశ్న 7
A thin cylindrical pressure vessel has mean diameter 1200 mm and is subjected to an internal pressure of 2 MPa. If the allowable hoop stress is 120 MPa, what minimum wall thickness is required based only on hoop stress?
Explanation:
For hoop-stress design, σh = pd/(2t). Rearranging gives t = pd/(2σh). Substitution gives t = 2 × 1200/(2 × 120) = 10 mm. This calculation addresses the membrane hoop-stress criterion only. It does not include corrosion allowance, joint efficiency or other code-required design factors, so Option C is correct.
వివరణ:
Question 8
ప్రశ్న 8
A thin cylinder has mean diameter 1000 mm and wall thickness 8 mm. If the allowable hoop stress is 150 MPa, what internal pressure is permissible based only on the hoop-stress criterion?
Explanation:
The hoop-stress relation is σh = pd/(2t). Solving for pressure gives p = 2tσh/d. Substitution gives p = 2 × 8 × 150/1000 = 2.4 MPa. The longitudinal stress at this pressure would be only one-half of the hoop stress for a closed-end cylinder. Therefore Option C is correct.
వివరణ:
Question 9
ప్రశ్న 9
For a thin closed-end cylinder made of an isotropic linear-elastic material, radial stress being neglected, which expressions correctly give circumferential strain εh and longitudinal strain εl?
Explanation:
The wall of a thin closed cylinder is approximately in a biaxial plane-stress state consisting of hoop and longitudinal normal stresses. For an isotropic linear-elastic material, strain in one direction includes direct strain caused by stress in that direction and Poisson contraction caused by the perpendicular stress. Therefore εh = (σh - νσl)/E. Similarly, εl = (σl - νσh)/E. Hence Option A is correct.
వివరణ:
Question 10
ప్రశ్న 10
A thin closed-end cylinder has d = 1000 mm, t = 10 mm, p = 2 MPa, E = 200 GPa and Poisson's ratio ν = 0.30. What are the circumferential and longitudinal strains?
Explanation:
The pressure stresses are σh = 100 MPa and σl = 50 MPa. Circumferential strain is (100 - 0.30 × 50)/200000 = 0.000425. This is 425 microstrain. Longitudinal strain is (50 - 0.30 × 100)/200000 = 0.000100, or 100 microstrain. Therefore Option B is correct.
వివరణ:
Question 11
ప్రశ్న 11
For the cylinder in the previous question, if its original length is 2000 mm, what are the approximate increases in diameter and length?
Explanation:
Circumferential strain equals the fractional change in circumference and therefore also equals the fractional change in diameter for small deformation. Thus Δd = εh d = 0.000425 × 1000 = 0.425 mm. The longitudinal change is ΔL = εl L. Substitution gives ΔL = 0.000100 × 2000 = 0.200 mm. Hence Option C is correct.
వివరణ:
Question 12
ప్రశ్న 12
For a thin closed-end cylindrical vessel undergoing small elastic deformation, which expression gives the approximate volumetric strain of the enclosed cylindrical volume in terms of circumferential strain εh and longitudinal strain εl?
Explanation:
The enclosed cylindrical volume is proportional to d²L. For small changes, the fractional change in d² is approximately twice the fractional change in diameter. The fractional diameter change is represented by the circumferential strain εh. The fractional length change is εl. Therefore the first-order volumetric strain is εv = 2εh + εl, making Option B correct.
వివరణ:
Question 13
ప్రశ్న 13
A thin closed-end cylinder has mean diameter d = 1000 mm, length L = 2000 mm, t = 10 mm, p = 2 MPa, E = 200 GPa and ν = 0.30. Using the elementary thin-wall approximation V ≈ πd²L/4 based on the given mean diameter, what are the approximate volumetric strain and increase in enclosed volume?
Explanation:
For this vessel, εh = 0.000425 and εl = 0.000100. Therefore εv = 2εh + εl = 0.000950. Under the approximation explicitly stated in the question, the reference volume is πd²L/4 ≈ 1.5708 × 10^9 mm³, or about 1570.8 litres. Multiplying this reference volume by 0.000950 gives an approximate increase of 1.49 litres. Therefore Option B is correct within the stated elementary thin-wall approximation.
వివరణ:
Question 14
ప్రశ్న 14
A thin closed cylinder has d = 1000 mm, t = 10 mm and p = 2 MPa, giving σh = 100 MPa and σl = 50 MPa. If E = 200 GPa and the measured increase in diameter is 0.425 mm, what value of Poisson's ratio is implied?
Explanation:
The measured circumferential strain is Δd/d = 0.425/1000 = 0.000425. The biaxial strain relation is Eεh = σh - νσl. Therefore 200000 × 0.000425 = 100 - 50ν. This gives 85 = 100 - 50ν and hence ν = 0.30. Therefore Option C is correct.
వివరణ:
Question 15
ప్రశ్న 15
A closed thin cylinder has mean diameter 1000 mm, thickness 10 mm, E = 200 GPa and ν = 0.30. If its measured circumferential strain due solely to internal pressure is 425 microstrain, what is the internal pressure?
Explanation:
For a closed cylinder, σh = pd/(2t) and σl = pd/(4t). Therefore εh = (σh - νσl)/E = pd(2 - ν)/(4tE). Solving for p gives p = 4tEεh/[d(2 - ν)]. Substitution of the stated values gives p = 2.0 MPa. Hence Option C is correct.
వివరణ:
Question 16
ప్రశ్న 16
For a thin spherical pressure vessel of mean diameter d, wall thickness t and internal pressure p, what is the membrane tensile stress in the shell?
Explanation:
A thin spherical shell has equal membrane stress in all tangential directions because of its geometric symmetry. Equilibrium of one hemisphere gives the internal pressure force acting over the projected circular area. This force is resisted by membrane tension around the great-circle cut. The resulting thin-shell relation is σ = pd/(4t). Therefore Option B is correct.
వివరణ:
Question 17
ప్రశ్న 17
A thin spherical vessel has mean diameter 1000 mm, thickness 10 mm and internal pressure 2 MPa. What tangential membrane stress is developed?
Explanation:
For a thin spherical shell, σ = pd/(4t). Substitution gives σ = 2 × 1000/(4 × 10). This equals 50 MPa. The corresponding hoop stress in a cylindrical vessel of the same diameter, thickness and pressure would be 100 MPa. Therefore Option B is correct.
వివరణ:
Question 18
ప్రశ్న 18
The spherical vessel in the previous question is made of a material with E = 200 GPa and ν = 0.30. What are the tangential strain and approximate increase in diameter?
Explanation:
A thin spherical wall has equal tangential stresses σ in two mutually perpendicular surface directions. The strain in either tangential direction is therefore ε = (σ - νσ)/E = σ(1 - ν)/E. With σ = 50 MPa, E = 200000 MPa and ν = 0.30, the strain is 0.000175. The corresponding diameter increase is εd = 0.000175 × 1000 = 0.175 mm. Therefore Option B is correct.
వివరణ:
Question 19
ప్రశ్న 19
A thin cylindrical vessel and a thin spherical vessel have the same mean diameter, wall thickness and internal pressure. How does the cylinder hoop stress compare with the spherical membrane stress?
Explanation:
The hoop stress in a thin cylinder is pd/(2t). The membrane stress in a thin sphere is pd/(4t). Dividing the cylindrical hoop stress by the spherical stress gives a ratio of two. Thus, for equal pressure and geometry, the sphere carries the pressure more efficiently in terms of membrane stress. Therefore Option C is correct.
వివరణ:
Question 20
ప్రశ్న 20
A thin cylinder and a thin sphere have the same diameter and are designed for the same internal pressure and allowable membrane stress. Based only on the elementary pressure-stress criterion, how do their required wall thicknesses compare?
Explanation:
For a cylinder governed by hoop stress, the required thickness is t = pd/(2σallow). For a sphere, the corresponding requirement is t = pd/(4σallow). The cylindrical requirement is therefore twice the spherical requirement for equal p, d and allowable stress. This comparison is based solely on the elementary membrane-stress equations and excludes practical design allowances. Therefore Option C is correct.
వివరణ:
Question 21
ప్రశ్న 21
A thin closed-end cylindrical vessel has d = 1000 mm and t = 10 mm. If the allowable hoop stress is 120 MPa and the allowable longitudinal stress is 80 MPa, what maximum internal pressure satisfies both limits?
Explanation:
The hoop-stress limit gives p = 2tσh,allow/d = 2 × 10 × 120/1000 = 2.4 MPa. The longitudinal-stress limit gives p = 4tσl,allow/d = 4 × 10 × 80/1000 = 3.2 MPa. Both criteria must be satisfied simultaneously. Therefore the smaller permissible pressure of 2.4 MPa governs. Hence Option C is correct.
వివరణ:
Question 22
ప్రశ్న 22
Which statement best explains why radial stress is usually neglected in elementary thin-cylinder membrane analysis?
Explanation:
At the inner wall surface, radial stress is related to the applied internal pressure and is not generally zero. At an unloaded outer surface it approaches the external pressure, often approximately zero gauge pressure. Thus radial stress changes through the thickness rather than remaining exactly zero. In a sufficiently thin vessel, hoop and longitudinal membrane stresses are much larger because of the large diameter-to-thickness ratio. Consequently Option B gives the correct reason for neglecting radial stress in elementary thin-shell analysis.
వివరణ:
Question 23
ప్రశ్న 23
Consider the following statements about thin pressure vessels:
1. In a closed thin cylinder under internal pressure alone, hoop stress is twice longitudinal stress.
2. For an ideal open-ended thin tube with no axial end load, internal pressure produces hoop stress but no longitudinal pressure stress.
3. A thin spherical shell develops equal tangential membrane stresses in mutually perpendicular surface directions.
4. The radial stress is assumed to be larger than the hoop stress in the thin-wall approximation.
Which statements are correct?
1. In a closed thin cylinder under internal pressure alone, hoop stress is twice longitudinal stress.
2. For an ideal open-ended thin tube with no axial end load, internal pressure produces hoop stress but no longitudinal pressure stress.
3. A thin spherical shell develops equal tangential membrane stresses in mutually perpendicular surface directions.
4. The radial stress is assumed to be larger than the hoop stress in the thin-wall approximation.
Which statements are correct?
Explanation:
Statement 1 is correct because pd/(2t) is twice pd/(4t). Statement 2 is correct because an open-ended tube has no pressure-loaded end closure producing an axial shell resultant. Statement 3 is correct because spherical symmetry gives equal membrane stresses in two mutually perpendicular tangential directions. Statement 4 is incorrect because radial stress is normally small compared with membrane stresses in a genuinely thin shell. Therefore Statements 1, 2 and 3 are correct and Option B is the unique answer.
వివరణ:
Question 24
ప్రశ్న 24
Match each thin-pressure-vessel quantity with its uniquely described elementary relationship, using mean diameter d:
1. Closed-cylinder hoop stress
2. Closed-cylinder longitudinal pressure stress
3. Thin-sphere tangential membrane stress
4. Small volumetric strain of the cylindrical enclosed volume
P. pd/(2t), acting circumferentially in the cylinder
Q. pd/(4t) = σh/2, acting axially in a closed cylinder
R. pd/(4t), acting equally in mutually perpendicular tangential directions of a sphere
S. 2εh + εl
Which matching is correct?
1. Closed-cylinder hoop stress
2. Closed-cylinder longitudinal pressure stress
3. Thin-sphere tangential membrane stress
4. Small volumetric strain of the cylindrical enclosed volume
P. pd/(2t), acting circumferentially in the cylinder
Q. pd/(4t) = σh/2, acting axially in a closed cylinder
R. pd/(4t), acting equally in mutually perpendicular tangential directions of a sphere
S. 2εh + εl
Which matching is correct?
Explanation:
The hoop membrane stress of a thin cylinder is pd/(2t), so item 1 matches P. The longitudinal pressure stress of a closed thin cylinder is pd/(4t) and acts axially, so item 2 matches Q. A thin sphere also has the numerical expression pd/(4t), but it represents equal tangential membrane stresses and therefore uniquely matches R. The first-order cylindrical volumetric strain is 2εh + εl, so item 4 matches S. Therefore Option A gives the unique correct matching.
వివరణ:
Question 25
ప్రశ్న 25
A thin closed-end cylinder has mean diameter 800 mm, wall thickness 8 mm, length 3000 mm and internal pressure 1.5 MPa. If E = 200 GPa and ν = 0.30, which set of values is correct?
Explanation:
The hoop stress is 1.5 × 800/(2 × 8) = 75 MPa, and the longitudinal stress is 37.5 MPa. Circumferential strain is (75 - 0.30 × 37.5)/200000 = 0.00031875, giving Δd = 0.255 mm. Longitudinal strain is (37.5 - 0.30 × 75)/200000 = 0.000075, giving ΔL = 0.225 mm. All four quantities therefore agree with Option B, making it the correct answer.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. The wall thickness is small compared with the vessel diameter, so membrane stresses may be treated as approximately uniform through the thickness and radial stress is small compared with the principal membrane stresses. సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: A. σh = pd/(2t) సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: B. σl = pd/(4t) సమాధానం: B.
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Question 4 ప్రశ్న 4Answer: C. σh = 2σl సమాధానం: C.
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Question 5 ప్రశ్న 5Answer: B. Hoop stress pd/(2t) but no longitudinal pressure stress సమాధానం: B.
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Question 6 ప్రశ్న 6Answer: B. σh = 100 MPa and σl = 50 MPa సమాధానం: B.
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Question 7 ప్రశ్న 7Answer: C. 10 mm సమాధానం: C.
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Question 8 ప్రశ్న 8Answer: C. 2.4 MPa సమాధానం: C.
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Question 9 ప్రశ్న 9Answer: A. εh = (σh - νσl)/E and εl = (σl - νσh)/E సమాధానం: A.
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Question 10 ప్రశ్న 10Answer: B. εh = 425 microstrain and εl = 100 microstrain సమాధానం: B.
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Question 11 ప్రశ్న 11Answer: C. Δd = 0.425 mm and ΔL = 0.200 mm సమాధానం: C.
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Question 12 ప్రశ్న 12Answer: B. εv = 2εh + εl సమాధానం: B.
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Question 13 ప్రశ్న 13Answer: B. εv = 0.000950 and ΔV ≈ 1.49 L సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: C. 0.30 సమాధానం: C.
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Question 15 ప్రశ్న 15Answer: C. 2.0 MPa సమాధానం: C.
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Question 16 ప్రశ్న 16Answer: B. σ = pd/(4t) సమాధానం: B.
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Question 17 ప్రశ్న 17Answer: B. 50 MPa సమాధానం: B.
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Question 18 ప్రశ్న 18Answer: B. ε = 0.000175 and Δd = 0.175 mm సమాధానం: B.
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Question 19 ప్రశ్న 19Answer: C. The cylinder hoop stress is twice the spherical stress. సమాధానం: C.
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Question 20 ప్రశ్న 20Answer: C. The cylinder requires twice the spherical thickness. సమాధానం: C.
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Question 21 ప్రశ్న 21Answer: C. 2.4 MPa సమాధానం: C.
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Question 22 ప్రశ్న 22Answer: B. Radial stress is compressive at the inner surface and changes through the thickness, but for a sufficiently thin wall its magnitude is small compared with the much larger hoop and longitudinal membrane stresses. సమాధానం: B.
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Question 23 ప్రశ్న 23Answer: B. 1, 2 and 3 only సమాధానం: B.
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Question 24 ప్రశ్న 24Answer: A. 1-P, 2-Q, 3-R, 4-S సమాధానం: A.
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Question 25 ప్రశ్న 25Answer: B. σh = 75 MPa, σl = 37.5 MPa, Δd ≈ 0.255 mm and ΔL ≈ 0.225 mm సమాధానం: B.
