These 40 MCQs are designed to cover a broad range of topics within Machine Design, including material properties, design principles, specific component design, and failure analysis. They are suitable for assessing knowledge in both academic and practical contexts.
1. What is the factor of safety in machine design?
Answer:
Explanation:
The factor of safety in machine design is the ratio of the breaking stress (or ultimate stress) of a material to the working stress (or allowable stress).
2. Which of the following is not a common failure mode in machine elements?
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Explanation:
Elasticity is not a failure mode; it is a material property. Fatigue, corrosion, and creep are common failure modes in machine elements.
3. In gear design, what does the term 'module' refer to?
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Explanation:
In gear design, the module is defined as the ratio of the pitch diameter to the number of teeth.
4. Which type of fit is preferred for parts that need to be assembled and disassembled frequently?
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Explanation:
Clearance fit is preferred for parts that need to be assembled and disassembled frequently as it allows for easy fitting and removal.
5. The endurance limit of a material is the:
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Explanation:
The endurance limit is the maximum stress level that a material can sustain for an infinite number of cycles without failing due to fatigue.
6. What is the primary consideration in the selection of materials for a spring?
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Explanation:
High fatigue strength is crucial for springs since they undergo numerous cycles of loading and unloading, making fatigue strength a primary consideration.
7. In a bolted joint, the function of a washer is to:
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Explanation:
The purpose of a washer in a bolted joint is to distribute the load over a larger area, reducing the pressure on the material being clamped.
8. The S-N curve in fatigue analysis represents the relationship between:
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Explanation:
The S-N curve (Stress-Number curve) in fatigue analysis represents the relationship between the stress applied to a material and the number of cycles to failure.
9. Which bearing type is typically used for high-load, low-speed applications?
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Explanation:
Plain bearings are typically used for high-load, low-speed applications due to their ability to distribute loads over a larger surface area.
10. In shaft design, the term 'key' refers to:
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Explanation:
A key is a machine element used to connect a rotating machine element to a shaft, preventing relative motion between the two.
11. Which type of stress is dominant in a thin-walled pressure vessel?
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Explanation:
In thin-walled pressure vessels, hoop stress (circumferential stress) is dominant due to the internal pressure acting outward radially.
12. What is the primary function of a coupling in a machine?
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Explanation:
The primary function of a coupling is to connect two shafts together, allowing them to transmit power while accommodating misalignment, end movement, or both.
13. In a belt drive system, the power transmission capacity increases with:
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Explanation:
The power transmission capacity of a belt drive system increases with an increase in belt speed, as it allows more material to pass over the pulleys per unit time.
14. What is the primary purpose of fins in heat exchanger design?
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Explanation:
Fins in a heat exchanger are used to increase the surface area, thereby enhancing the heat transfer rate between fluids.
15. In a rolling contact bearing, what is the purpose of the cage?
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Explanation:
The cage in a rolling contact bearing maintains the position of the rolling elements (like balls or rollers), keeping them evenly spaced and preventing them from clumping together.
16. The Lewis equation is used in the design of:
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Explanation:
The Lewis equation is a formula used in the design of gears, particularly in calculating the strength of gear teeth.
17. In a clutch, the term 'clutch engagement' refers to:
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Explanation:
Clutch engagement refers to the point at which the clutch plates come into contact and start transmitting power from the engine to the drivetrain.
18. The phenomenon of 'creep' in belt drives refers to:
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Explanation:
Creep in belt drives refers to the slight relative motion between the belt and the pulley due to the differences in tension on the two sides of the belt.
19. Which material is commonly used for manufacturing gears in high-speed applications?
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Explanation:
Stainless steel is commonly used for manufacturing gears in high-speed applications due to its high strength, corrosion resistance, and ability to withstand high temperatures.
20. The term 'hardness' in material science refers to:
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Explanation:
Hardness in material science refers to the ability of a material to resist wear, abrasion, indentation, and scratching.
21. In a hydraulic system, the main function of the accumulator is to:
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Explanation:
The accumulator in a hydraulic system is used to store hydraulic energy and maintain pressure in the system, especially when there are variations in the load.
22. A 'bevel gear' is primarily used for transmitting power between:
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Explanation:
Bevel gears are used to transmit power between intersecting shafts, typically at a 90-degree angle but can be designed for other angles as well.
23. In material selection, the term 'ductility' refers to the ability of a material to:
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Explanation:
Ductility refers to the ability of a material to undergo significant plastic deformation before rupture, often exemplified by its ability to be stretched into a wire.
24. The 'Poisson's ratio' of a material is the ratio of:
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Explanation:
Poisson's ratio is the ratio of transverse strain (contraction or expansion) to longitudinal strain (elongation) in a material subjected to uniaxial stress.
25. In a bolted connection, the term 'preload' refers to:
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Explanation:
Preload in a bolted connection is the initial tension introduced in the bolt when it is tightened. It is crucial for the bolt's performance and the integrity of the connection.
26. A 'helical spring' is designed to absorb which type of load?
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Explanation:
A helical spring is primarily designed to absorb axial loads, meaning loads applied along the axis of the spring.
27. In a worm gear mechanism, the 'worm' is:
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Explanation:
In a worm gear mechanism, the worm is a gear with a spiral thread that meshes with the worm wheel to transmit power.
28. The term 'resilience' of a material refers to its ability to:
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Explanation:
Resilience is the ability of a material to absorb energy during elastic deformation and release that energy upon unloading, returning to its original shape.
29. A 'cotter joint' is typically used for:
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Explanation:
A cotter joint is used to connect two coaxial rods or shafts and is suitable for transmitting axial loads.
30. The term 'yield strength' of a material refers to:
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Explanation:
Yield strength is the amount of stress at which a material begins to deform plastically. Beyond this point, the material will deform permanently and cannot return to its original shape.
31. A 'knuckle joint' is generally used for:
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Explanation:
A knuckle joint is typically used to connect two rods which are under tensile loads and is common in applications like connecting rod ends.
32. The 'Buckingham equation' is used in the field of machine design for calculating:
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Explanation:
The Buckingham equation is a formula used to calculate the strength of gear teeth, considering factors like gear material, size, and load.
33. In a 'leaf spring', the longest leaf is known as the:
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Explanation:
In a leaf spring, the longest leaf, which usually contains the spring eye for mounting, is referred to as the master leaf.
34. In fatigue analysis, 'Miner's rule' is used to:
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Explanation:
Miner's rule is a method used in fatigue analysis to predict the life of a component subjected to variable loading conditions.
35. In a lubrication system, the function of an 'oil ring' is to:
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Explanation:
An oil ring in a lubrication system is used to transport oil from the sump to the bearing surface, ensuring proper lubrication.
36. The 'Mohr's circle' is used in machine design to:
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Explanation:
Mohr's circle is a graphical method used in stress analysis to determine and visualize the state of stress at a point in a material.
37. A 'pinion' is:
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Explanation:
In a gear train, the pinion is the smaller gear, which often drives a larger gear or rack.
38. 'Creep strength' of a material refers to its ability to:
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Explanation:
Creep strength is the ability of a material to resist gradual permanent deformation under a constant load over a period, especially at high temperatures.
39. In a 'spur gear', the teeth are cut:
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Explanation:
In a spur gear, the teeth are cut parallel to the axis of rotation, making them straight and aligned with the axis.
40. The 'coefficient of friction' in machine design is used to calculate:
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Explanation:
The coefficient of friction is a dimensionless scalar value used to represent the resistance to sliding between two surfaces in contact. It is a crucial factor in the design of various machine elements where sliding motion occurs.