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Free download in PDF Design of Machine Elements Multiple Choice Questions and Answers for competitive exams. These short objective type questions with answers are very important for competitive exams. These short solved questions or quizzes are provided by Gkseries.
(1)
Why are rigid couplings used?
[A]
To connect diesel engine and generator
[B]
To connect eccentric shafts
[C]
To connect electric motor to pump
[D]
None of the above
Answer: To connect electric motor to pump
(2)
Calculate fatigue stress concentration factor, when theoretical stress concentration factor is 1.62 and notch sensitivity is equal to 0.9
[A]
1.558
[B]
3.358
[C]
1.162
[D]
None of the above
(3)
Line joining Syt (yield strength of the material) on mean stress axis and Se (endurance limit of the component) on stress amplitude axis is called as _____
[A]
Goodman line
[B]
Soderberg line
[C]
Gerber line
[D]
None of the above
(4)
According to Modified Goodman Diagram for fluctuating torsional shear stress, which line defines fatigue failure?
[A]
Line joining point Sys on mean stress and stress amplitude
[B]
Horizontal line QR at point Ses on stress amplitude
[C]
Polyline STRQ defines fatigue failure
[D]
None of the above
Answer: Horizontal line QR at point Ses on stress amplitude
(5)
To predict failure in design components which failure criteria is not assumed, when mean stress and stress amplitude are nonzero?
[A]
Goodman criterion
[B]
Soderberg criteria
[C]
Gerber criteria
[D]
None of the above
Answer: None of the above
(6)
A triple start square threaded power screw has torsional shear stress and direct compressive stress of 5 N/mm2 and 7 N/mm2. Calculate maximum shear stress induced in a screw body.
[A]
7.4 N/mm2
[B]
3.5 N/mm2
[C]
6.10 N/mm2
[D]
5 N/mm2
(7)
In power screws, if friction angle Φ is less than lead angle λ, then the screw undergoes _______
[A]
over hauling
[B]
self locking
[C]
both a. and b.
[D]
none of the above
(8)
The efficiency of power screw can be improved if ______
[A]
the rolling friction is replaced by sliding friction in the screw threads
[B]
the sliding friction is replaced by rolling friction in the screw threads
[C]
both a. and b.
[D]
none of the above
Answer: the sliding friction is replaced by rolling friction in the screw threads
(9)
Calculate torque required to overcome thread friction if axial load of 8 kN acts on a power screw having double start square threads of 30 mm mean diameter. Friction angle and lead angle are 7o and 9o respectively
[A]
68.81 N-m
[B]
41.90 N-m
[C]
34.40 N-m
[D]
Insufficient data
(10)
Which type of stress is induced in a screw body?
[A]
Bearing pressure
[B]
Direct shear stress
[C]
Torsional shear stress
[D]
None of the above
Answer: Torsional shear stress
(11)
What is the approximate nominal diameter for coarse threads?
[A]
d = 1.136 dc
[B]
d = 1.59 dc
[C]
d = 1.19 dc
[D]
d = 0.5 dc
(12)
Drilling axial hole is a method used to achieve ______
[A]
uniform strength
[B]
uniform stress
[C]
uniform toughness
[D]
all of the above
(13)
Threads used in screw fasteners are ______
[A]
having high strength
[B]
having low efficiency
[C]
single start type
[D]
all of the above
(14)
Which among the following is the condition to avoid separation of connected members?
[A]
Force acting on the connected members should be negative
[B]
Force acting on the connected members should be positive
[C]
Force acting on the connected members should be neither positive nor negative
[D]
None of the above
Answer: Force acting on the connected members should be negative
(15)
When a coupler nut is subjected to crushing stress, crushing failure can be avoided if _____
[A]
crushing stress induced is more than permissible crushing stress in the nut
[B]
permissible crushing stress is more than crushing stress induced in the threads
[C]
crushing stress induced is equal to permissible crushing stress
[D]
all of the above
Answer: permissible crushing stress is more than crushing stress induced in the threads
(16)
Universal coupling is a type of ____
[A]
Flexible coupling
[B]
Rigid coupling
[C]
Both a. and b.
[D]
None of the above
Answer: Flexible coupling
(17)
According to A.S.M.E code what is the allowable shear stress for a shaft without keyway effect, which has ultimate tensile strength and yield strength of 300 N/mm2 and 150 N/mm2 respectively.
[A]
45 N/mm2
[B]
54 N/mm2
[C]
40.5 N/mm2
[D]
None of the above
(18)
A shaft transmits power of 30 kW. According to maximum principle stress theory and shear theory diameter of shaft is 70 mm and 73 mm respectively. Tensile stress acting on the shaft is 50 Mpa. What will be the shaft diameter to transmit power?
[A]
65 mm
[B]
70 mm
[C]
73 mm
[D]
Insufficient data
(19)
Calculate diameter of shaft using maximum principle stress theory, when equivalent bending moment of 900 x 103 N-mm acts on the shaft when maximum tensile stress does not exceed 50 N/mm2 and equivalent torque of 700 N-m acts on it.
[A]
56.80 mm
[B]
52.24 mm
[C]
50 mm
[D]
None of the above
(20)
Which formula is used if slenderness ratio Le / K < X, where X = √ ( 2π 2 E / Syc )?
[A]
Euler's formula
[B]
J. B. Johnson formula
[C]
Rankine formula
[D]
None of the above
Answer: J. B. Johnson formula
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