Dme mcq

Design of Machine Elements MCQ

1. GRT INSTITUTE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF MECHANICAL ENGINEERING
III YEAR - ODD SEMESTER 2020-2021
Design of Machine Elements Multiple choice questions

UNIT - I
1. The toughness of a material __________ when it is heated.
A. increases
B. decreases
C. does not change
2. Soderberg relation is based on __________ of the material whereas all other
failure relation for dynamic loading are based on ultimate strength of the
material.
A. elastic strength
B. yield strength
C. shear strength
D. Ultimate Strength
3. The value of stress concentration factor depends upon
A. material of the part
B. geometry of the part
C. material and geometry of the part
D. none of these
4. Surface endurance limit of gear material is dependent upon its
A. elastic strength
B. yield strength
C. brinell hardness number
D. toughness
5. Stress concentration is caused due to
A. variations in load acting on a member
B. variations in properties of materials in a member
C. abrupt change of cross-section

2. D. all of these
6. The maximum normal stress theory is used for
A. brittle materials
B. ductile materials
C. plastic materials
D. non-ferrous materials

7. The maximum shear stress theory is used for
A. brittle materials
B. ductile materials
C. plastic materials
D. non-ferrous materials

8. The ratio of the ultimate stress to the design stress is known as
A. elastic limit
B. strain
C. factor of safety
D. bulk modulus

9. Stress concentration factor is defined as the ratio of
A. maximum stress to the endurance limit
B. nominal stress to the enurance limit
C. maximum stress to the nominal stress
D. nominal stress to the maximum stress

10. Which of the following welded joint is designed for shear strength ?
A. Transverse fillet welded joint
B. Parallel fillet welded joint
C. Butt welded joint
D. all of these

11. Why is the maximum stress applied to any machine element should always be
less than its ultimate stress or critical stress?
A. for safety against machine failure
B. to make complete use of mechanical properties of the machine element
C. both a and b

3. D. none of the above

UNIT - II
1. The sleeve or muff coupling is designed as a
A. dun cylinder
B. thick cylinder
C. solid shaft
D. hollow shaft
2. Which of the following statement is correct?
A. A parallel sunk key is a taperless key
B. A parallel sunk key may be rectangular or square in cross-section
C.
A flat saddle key is a taper key which fits in a key way of the hub and is flat on the
shaft
D. all of the above

3. In a flange coupling, the flanges are coupled together by means of
A. bolts and nuts
B. studs
C. headless taper bolts
D. none of these
4. A transmission shaft includes
A. counter shaft
B. line shaft
C. over head shaft
D. all of these
5. In designing a sleeve coupling, length of the sleeve is taken as (where d =
Diameter of the shaft)
A.
d + 17 mm
B.
2 d + 13 mm
C.
2 d + 20 mm

4. D.
3.5 d

6. An universal coupling is used to connect two shafts
A. which are perfectly aligned
B. which are not in exact alignment
C. have lateral misalignment
D. whose axes intersect at a small angle

7. A taper key which fits half in the key way of the hub and half in the key way of shaft, is
known as
A. sunk key
B. flat saddle key
C. hollow saddle key
D. tangent key

8. 8. In a marine flange coupling, the thickness of flange is taken as
A. d/4
B. d/3
C. d/2
D. 3 d/4

9. A wood-ruff key is
A.
a tapered key with head at one end
B.
fitted in pairs at right angles
C.
capable of tilting in a recess milled out in the shaft
D.
all of the above

10. The bolts in a rigid flanged coupling connecting two shafts transmitting power
are subjected to
A. Shear force and bending moment diagram
B. Axial force
C. Torsion
D. Torsion and bending moment

5. 11. For a square key made of mild steel, the shear and crushing strengths are
related as
A. shear strength = crushing strength C. shear strength > crushing strength
B. shear strength < crushing strength D. None of the above
12. A keyway lowers
A. The strength of the shaft
B. The rigidity of the shaft
C. Both the strength and rigidity of the shaft
D. The ductility of the material of the shaft
13. Oldham coupling is used to connect two shafts
A. Which are perfectly aligned
B. Which are not in exact alignment
C. Which have lateral misalignment
D. Whose axes intersect at a small angle
14. Two shafts will have equal strength, if
A. Diameter of both the shafts is same
B. Angle of twist of both the shafts is same
C. Material of both the shafts is same
D. Twisting moment of both the shafts is same
15. The design of shafts made of brittle materials is based on
A. Guest’s theory B. Rankine’s theory
C. St. Venant’s theory D. Von Mises Theory

UNIT - III
1. Screws used for power transmission should have
A. Low efficiency
B. high efficiency
C. very fine threads
D. strong teeth
2. The number of slots in a 25 mm castle nut is
A. 2 B. 4 C. 6 D.8

6. 3. A locking device in which the bottom cylindrical portion is recessed to receive
the tip of the locking set screw, is called
A. castle nut
B. jam nut
C. ring nut
D. sawn nut
4. When screw threads are to be used in a situation where power is being
transmitted in one direction only, then the screw threads suitable for this will be
A. square threads
B. acme threads
C. knuckle threads
D. buttress threads
5. When a bolt is subjected to shock loading, the resilience of the bolt should be
considered in order to prevent breakage at the
A. head B. Shank C. Thread D. Middle
7. A cotter joint is used to transmit
A. axial tensile force only
B. axial tensile or compressive force
C. axial compressive force only
D. combined bending and torsional moment
8. A connecting rod is designed as a
A. long column
B. short column
C. strut
D. all of these

9. When a bolt and nut is made of mild steel, then the effective height of nut is
made equal to (where d = Nominal diameter of bolt)


A. 0.5 d C. d
B. 0.75 d D. 1.25 d
10. Weldments in fabricated steel beams are designed for
A. Bending Stress at the flange

7. B. Shear stress at transverse plane
C. Combination of bending and shear
D. None of the above
11. In designing a sleeve and cotter joint, the outside diameter of the sleeve is
taken as
A. 1.5 d B. 2.5 d C. 3d D. 4d
12. In a steam engine, the piston rod is usually connected to the crosshead by
means of a
A. Knuckle joint B. Universal joint
C. Flange coupling D. Cotter joint
13. In a turn buckle, if one of the rods has left hand threads, then other rod will
A. Right hand threads B. Left hand threads
C. Pointed threads D. Multiple threads
14. When one gib is used in a gib and cotter joint, then width of gib should be
A. 0.45 B B. 0.55 B C. 0.65 B D. 0.75 B
15. Which of the following formula is used in designing a connecting rod ?
(a) Euler’s formula (b) Rankine’s formula
(c) Johnson’s straight line formula (d) Johnson’s parabolic formula
16.. A screw is said to be over hauling screw, if its efficiency is
A. less than 50%
B. more than 50%
C. equal to 50%
D. none of these
UNIT – IV
1. A crankshaft is a __________ shaft.
A. Transmission B. Machine
2. In leaf springs, the longest leaf is known as
A. Lower leaf C. Upper leaf
B. Master leaf D. None of these

8. 3. When spring index increases, the value of Wahl's stress factor
A. Increases linearly C. Reamains Same
B. Decreases linearly D. Increases Exponentially

4. The cracks in helical springs used in railway carriages usually start on the inner
side of the coil because of the fact that
A. It is subjected to a higher stress than the outer side
B. It is subjected to a higher cyclic loading than the outer side
C. It is more stretched than the outer side during the manufacturing process
D. It has a lower curvature than the outer side

5. Which of the following spring is used in mechanical wrist watch?
A. Helical compression spring C. Torsion spring
B. Spiral Spring D. Bellevile spring

6. The maximum fluctuation of speed is the
A. Difference of minimum fluctuation of speed and the mean speed
B. Difference of the maximum and minimum speeds
C. Sum of the maximum and minimum speeds
D. variations of speed above and below the mean resisting torque line
7. The coefficient of fluctuation of speed is the ........... of maximum fluctuation of
speed and the mean speed.
A. Product B. Ratio C. Sum D. Difference
8. In a turning moment diagram, the variations of energy above and below the mean
resisting torque line is called
A. Fluctuation of energy B. Maximum fluctuation of energy
C. Coefficient of fluctuation of energy D. none of these
9. Due to centrifugal force acting on the rim, the flywheel arms will be subjected to
A. Tensile stress B. Compressive stress
C. Shear stress D. None of these

9. 10. The spring mostly used in gramophones is
A. Helical spring B. Conical spring
C. Laminated spring D. Flat spiral spring
11. A leaf spring in automobiles is used
A. to apply forces B. to measure forces
C. to absorb shocks D. to store strain energy
12. When two concentric coil springs made of the same material, having same length
and compressed equally by an axial load, the load shared by the two springs will
be ............ to the square of the diameters of the wires of the two springs.
A. directly proportional B. inversely proportional
C. Equal to D. None
13. Two close coiled helical springs with stiffness k1 and k2 respectively are
connected in series. The stiffness of an equivalent spring is given by
Ans: (a)

UNIT – V
1. The ball bearings are provided with a cage
A. to reduce friction
B. to facilitate slipping of balls
C. to prevent the lubricant from flowing out
D. to maintain the balls at a fixed distance apart
2. In a hydrodynamic lubricated bearing
A. there is a thick film of lubricant between the journal and the bearing
B. there is a thin film of lubricant between the journal and the bearing
C. there is no lubricant between the journal and the bearing
D. the lubricant is forced between the journal and the bearing, by external pressure
3. The rolling contact bearings are known as
A. thick lubricated bearings
B. plastic bearings

10. C. thin lubricated bearings
D. antifriction bearings
4. The rolling contact bearings as compared to sliding contact bearings have
A. small overall dimensions
B. accuracy of shaft alignment
C. low starting and low running friction except at very high speeds
D. all of the above

5. The bearings of heavy series have capacity __________ over the medium series.
A. 10 to 20%
B. 20 to 30%
C. 30 to 40%
D. 40 to 50%


6. A sliding bearing which operates without any lubricant present, is called
A. zero film bearing
B. boundary lubricated bearing
C. hydrodynamic lubricated bearing
D. hydrostatic lubricated bearing

7. The metal suitable for bearings subjected to light loads is
A. silicon bronze
B. white metal
C. monel metal
D.
phosphor bronze


8. Which of the following is an antifriction bearing?
A. journal bearing
B. pedestal bearing
C. collar bearing
D. needle bearing

9. Tapered roller bearings can take

11. A. radial load only
B. axial load only
C. both radial and axial loads and the ratio of these being less than unity
D. both radial and axial loads and the ratio of these being greater than unity
10. When the length of the journal is equal to the diameter of the journal, then the
bearing is said to be a
A. short bearing
B. long bearing
C. medium bearing
D. square bearing

11. Antifriction bearings are
A. Thick lubricated bearings
B. Plastic bearings
C. Thin lubricated bearings
D. Ball and roller bearings

12. Which of the bearings given below SHOULD NOT be subjected to a thrust load?
A. Deep groove ball bearing
B. Angular Contact bearing
C. Cylindrical roller bearing
D. Single row tapered roller bearing
13. Which one of the following is criterion in the design of hydrodynamic journal bearings?
A. Sommerfeld number
B. Rating Life
C. Specify Dynamic Capacity
D. Rotation Factor
14. To restore stable operating condition in a hydrodynamic journal bearing, when it
encounters higher magnitude loads.
A. Oil Viscosity is to be decreased
B. Oil Viscosity is to be increased

12. C. Oil Viscosity index is to be decreased
D. Oil Viscosity index is to be increased
15. In thick film hydrodynamic journal bearings, the coefficient of friction
A. Increased with increase in load
B. Is Independent of load
C. Decrease with increase in load
D. May increase or decrease with increase in load
16. Spherical roller bearings are normally used
A. For Increase radial load
B. For increase thrust load
C. When there is less radial load
D. To compensate for angular Misalignment
17. If the load on a ball bearing is reduced to half, the life of the ball bearing will
A. Increase 8 times
B. Increase 4 times
C. Increase 2 times
D. No Change