INDIAN INSTITUTE OF TECHNOLOGY, KHARAGPUR
End/Mid Semester Examination
DESIGN OF MACHINE ELEMENTS
ME30602
Class Test
1. Answer all questions. All questions carry equal marks
2. Make suitable assumptions wherever necessary
3. Put √ on your chosen answer.
4. Any data, if not furnished, may be assumed.
1. A
new model of a car is a typical example of
a) Adaptive
design
b) Developmental
design
c) New design
2. Adaptive
design is based on
a)
Existing design adapted for new
application
b)
New inventions for new application
c)
Conceptual design for new application
d)
New Technology for new application
3. Which
of the following design is based on based on experience and experiments?
a)
Rational design
b)
Empirical design
c)
Industrial design
4. Use
of factor of safety in designing the elements is to
a)
optimize the design to avoid
over-design for reliability
b)
prevent loss of material and premature
failure
c)
have good aesthetics of the designed
product
d)
increase efficiency of the element
5. A
stainless steel is described as 18/8 steel. This indicates that it contains:
a)
8% Nickel and 18% Chromium
b)
18% Nickel and 8% Chromium
c)
18% Chromium and 8% Silicon
d)
8% Chromium and 18% Silicon
6. Resilience
is
a)
the property of the material that
enables it to resist shock and impact by storing energy
b)
the property of the material that
enables it to be twisted, bent or stretched under impact load or high stress
before rupture
c)
the property of the material that
enables it to be drawn out or elongated to an appreciable extent before rupture
d)
the property of the material that
enables it to resist permanent deformation, penetration, indentation
7. Resilience
is the property of a material:
a)
that enables it to resist indentation
b)
that enables it to resist wear
c)
that enables it to resist shock and
impact
d)
that enables it to resist scratching
8. A
standard alloy steel used for making engineering components is 20Cr18Ni2. The
composition of this steel is:
a)
20% carbon, 18% chromium and 2% nickel
b)
0.2% chromium, 18% nickel and 2% carbon
c)
0.2% carbon, 18% chromium and 2%
nickel
d)
20% chromium, 18% nickel and 2% carbon
9. The
composition of 20Cr18Ni2 is:
a)
20% Cr, 18%Ni, 2%Carbon
b)
0.2% carbon, 18% chromium and 2%
nickel
c)
2% Cr, 0.18%Ni, 0.2%Carbon
d)
2% carbon, 0.18% chromium and 0.2%
nickel
10.
Allowance of a shaft-hole system is the
difference between
a)
maximum dimension of shaft and minimum
dimension of hole
b)
maximum dimension of shaft and
maximum dimension of hole
c)
minimum dimension of shaft and minimum
dimension of hole
d)
minimum dimension of shaft and maximum
dimension of hole
11.
Tolerance
is the difference between:
a)
Maximum and minimum dimensions of a
component
b)
Maximum dimension of the shaft and
maximum dimensions of the hole
c)
Minimum and minimum dimensions of a
component
d)
Minimum dimension of the shaft and the
maximum dimension of the hole
12.
In a unilateral system of tolerance, the
tolerance is allowed on
a)
one side of the actual size
b)
one side of the nominal size
c)
both sides of the actual size
d)
both sides of the nominal size
13.
Nominal size of a hole and shaft is 40
mm, the tolerance grade for making the hole is IT6 and for shaft is IT5. The
fundamental deviation of shaft basis is positive and for hole is zero. Which of
the following designation suits the above hole-shaft system?
a)
40M6/h5
b)
40M5/h6
c)
40H5/m6
d)
40H6/m5
14.
Which of the following standard series
is used for Capacities of hydraulic cylinder?
a)
R5
b)
R10
c)
R20
d)
R40
15.
What is the bearing stress developed at the
faces of a rectangular key fixing a gear hub on a shaft acted upon by a torque
T as shown in figure?
16.
Let
the cross-sectional area of the plate, the larger hole H1 and the
smaller holes H2 be A, a1, a2 respectively. If
2a2 > a1 , the critical section in the loaded plate
is:
a)
A-A
b)
B-B
c)
C-C
d)
D-D
17.
A
3m long cantilever beam of solid rectangular cross-section of 100mm width and
150mm depth is subjected to an end loading P as shown in the figure. If the
allowable shear stress in the beam is 150 MPa, the safe value of P based on
shear alone is
a) 1
MN
b) 1.5
MN
c) 2.3
MN
d) 3.5
MN
18.
A
vertical load Py = 20 kN is applied at the free end of a cylindrical
bar of radius 50 mm as shown in figure. The principal stress at the point A is
a) 56MPa,
7.4MPa
b) 84MPa,
−8.9MPa
c) 105MPa,
9.3MPa
d) 112.5MPa,
−14.72MPa
19.
An
axially loaded brass (Ebrass = 90GPa) strut hinged at both ends is
1m long and is of a square cross-section of sides 20mm. The dimension of steel
(Esteel = 200 GPa) strut of the same length and subjected to the
same axial loads is:
a) 24.40
mm
b) 13.42
mm
c) 16.38
mm
d) 32.62
mm
20.
The
theoretical stress concentration factor at hole in a plate with transverse
elliptical hole and subjected to a tensile load as shown in figure is:
21.
Notch
sensitivity factor, q is
22.
The
endurance or fatigue limit is defined as the maximum value of the stress which
a polished standard specimen can withstand without failure, for infinite number
of cycles, when subjected to
a) static
load
b) dynamic
load
c) static
as well as dynamic load
d) completely
reversed load
23.
In
the plate shown below it is required that the stress concentration at hole does
not exceed that at the fillet. The hole diameter is
a) 21.5
mm
b) 35
mm
c) 41.9
mm
d) 53
mm
Data Provided:
24.
Dowel
pins are used for
a) proper
alignment
b) loosening
c) both
for proper alignment and loosening
25.
Dowel Pins are used
a) To
get a better grip
b) To
transmit torque smoothly
c) For
proper alignment
26.
Studs
are
a) single
headed fasteners
b) double
headed fasteners
c) headless
fasteners
d) twin
headed fasteners
27.
A
heat treated steel shaft of tensile yield strength of 350 MPa has a diameter of
50mm. The shaft rotates at 1000 rpm and transmits 100 kW through a gear. An
appropriate key set of dimensions is:
a) Width
= 16 mm, Length = 45 mm, Depth = 10 mm
b) Width
= 10 mm, Length = 35 mm, Depth = 8 mm
c) Width
= 18 mm, Length = 55 mm, thickness = 11 mm
d) Width
= 20 mm, Length = 65 mm, thickness = 12 mm
Data Provided:
|
Shaft Diameter
(mm)
|
30-38
|
38-44
|
44-50
|
50-58
|
58-65
|
65-75
|
75-85
|
|
Key width, w
(mm)
|
10
|
12
|
14
|
16
|
18
|
20
|
22
|
|
Key depth, t
(mm)
|
8
|
9
|
9
|
10
|
11
|
12
|
14
|
|
Key length, L
(mm)
|
22-110
|
28-140
|
36-160
|
45-180
|
50-200
|
56-220
|
63-250
|
28.
In
a steam engine the steam pressure is 2 MPa and the cylinder diameter is 250 mm.
The contact surfaces of the head and cylinder are ground and no packing is
required. Assuming that the number of bolts to be used is 12, a suitable bolt
for the joint to be leak proof would be:
a) M20
x 1.5
b) M16
x 1.5
c) M5
x 0.8
d) M10
x 1.25
Data provided:
|
Designation
|
Pitch
(mm)
|
Minor Diameter
|
Stress area
(mm2)
|
|
|
Bolt (mm)
|
Nut (mm)
|
|||
|
M2
|
0.40
|
1.509
|
1.567
|
207
|
|
M5
|
0.8
|
4.019
|
4.134
|
14.2
|
|
M10
|
1.25
|
8.466
|
8.647
|
61.6
|
|
M16
|
1.5
|
14.160
|
14.376
|
167
|
|
M20
|
1.5
|
18.160
|
18.376
|
272
|
|
M24
|
2
|
21.546
|
21.835
|
384
|
29.
Shear stress developed in the weld in the
figure shown below is
a) 16.7
MPa
b) 21.9
MPa
c) 26.2
MPa
30.
Considering unit weld width the polar moment
of inertia of the weld group in above question is
a) 0.00365
m3
b) 0.000198
m3
c) 0.0000325
m3
31.
If
the yield strength of the weld material is 150MPa, the safe value of F is
a) 108
kN
b) 213
kN
c) 269
kN
d) 313
kN
32.
In a triple riveted butt joint with two
unequal straps 30 mm diameter rivets and 10mm plates (both main and straps) are
used. The pitch at the outer row is 250mm. Considering that the joint fails
only due to shearing of all the rivets and taking the working stresses to be σt
= 75MPa, τy = 60MPa and σc = 130MPa, the joint efficiency
is
a) 76.3%
b) 81.3%
c) 98.3%
33.
Two
plates of 7 mm thickness are connected by a double riveted lap joint of zigzag pattern.
If the rivet diameter is 19mm and σt = 90MPa, σc =
120MPa, Ï„ = 60 MPa, the rivet pitch is
a) 19
mm
b) 54
mm
c) 73
mm
d) 102
mm
34.
According to Unwin's formula, the diameter of
the rivet hole (in mm) can be obtained by: (t
= thickness of the plate in mm)
35.
Wahl
correction factor takes care of:
a) curvature
effect
b) shear
stress correction
c) both
curvature effect and shear stress correction
36.
In spring design, Wahl correction factor
a) takes
care of the direct shear stress in springs
b) takes
care of the curvature effect in springs
c) takes
care of the direct stress together with the curvature effect in springs
37.
In
a close coiled helical spring, the spring index (C) is given by D/d where D and
d are the mean coil diameter and wire diameter respectively. For considering
the effect of curvature, the Wahl’s stress factor K is given by
38.
Which
of the following threads is used for transmission of power only in one
direction?
a) Acme
thread
b) Knuckle
thread
c) Buttress
thread
d) Square
thread
39.
V-threads are normally used for
a) power
transmission
b) for
securing two components
c) not
normally used
40.
A
bolt of M 24 × 2 means that
a) the
pitch of the thread is 24 mm and depth is 2 mm
b) the
cross-sectional area of the threads is 24 mm2 and number of starts
is 2
c) the
nominal diameter of bolt is 24 mm and the pitch is 2 mm
d) the
effective diameter of the bolt is 24 mm and there are two threads per cm
41.
The shear stress developed in the centre bolt
(no-2) is
a) 35.3
MPa
b) 43.6
MPa
c) 6.4
MPa
42.
For
zero collar friction, the efficiency of a square-thread screw is:
(λ is lead angle and f
is coefficient of friction of the screw)
43.
A
single square thread power screw is to raise a load of 50 kN. A screw thread of
major diameter of 34 mm and a pitch of 6 mm is used. The coefficient of
friction at the thread and collar are 0.15 and 0.1 respectively. If the collar
frictional diameter is 100 mm and the screw turns at a speed of 1 rev per
second. The power input to the screw is
a) 1549
watts
b) 2300
watts
c) 2614
watts
d) 3167
watts
44.
In the above question, the combined efficiency
of the screw and collar is
a) 11.5%
b) 22.3%
c) 33.5%
d) 44.3%
45.
The
machine shown in the figure can be used for a tension test but not for a
compression test. Should both screws have the same hand?
a) Yes
b) No,
screws should always have different hands
c) No,
screws can have either same or different hands
46.
In the machine shown below, both the screws
have the same hand
a) the
machine can be used for a compression test only
b) the
machine can be used for a tension test only
c) the
machine can be used for both tension and compression tests
47.
The purpose of Rebound clips in Laminated
semi-elliptic spring is:
a) to
share the load from the master leaf to the graduated leaf
b) to
hold the leaves of the spring
c) to
prevent the deflected spring from touching the attached machine member
d) to
attach the spring with another machine member
48.
The purpose of central clamp in Laminated
semi-elliptic spring is:
a) to
share the load from the master leaf to the graduated leaf
b) to
hold the leaves of the spring
c) to
prevent the deflected spring from touching the attached machine member
d) to
attach the spring with another machine member
49.
The purpose of camber in Laminated
semi-elliptic spring is:
a) to
share the load from the master leaf to the graduated leaf
b) to
hold the leaves of the spring
c) to
prevent the deflected spring from touching the attached machine member
d) to
attach the spring with another machine member
50.
Which of the following methods reduces
additional stresses in laminated spring hinged at supports?
a) Master
leaf is made of stronger material than the other leaves
b) Master
leaf is made thinner than the other leaves
c) Increase
the radius of curvature of the master leaf than the next leaf
d) All
the above
51.
Nipping
of leaf spring
a) Increases
the stress in master leaf
b) Decreases
the stress in master leaf
c) Doesn’t
affect the stress in master leaf
52.
A
helical spring of wire diameter 6mm and spring index 6 is acted by an initial
load of 800N. After compressing it further by 10mm the stress in the wire is
500MPa. Taking G = 84000MPa the number of active coils is
a) 13
turns
b) 21
turns
c) 27
turns
d) 32
turns
53.
For
a simple cantilever type leaf spring with uniform strength the leaf thickness
can be given by
a) σmax
L3/2/(E δmax1/2)
b) σmax
L3/(E δmax2)
c) σmax
L2/(E δmax)
d) σmax
L4/(E δmax3)
Where δmax
is the spring deflection, L is the characteristic length, σmax is
the design stress or maximum stress and E is the Modulus of elasticity
54.
Thermoplastic
materials are those materials which
a) are
formed into shape under heat and pressure and results in a permanently hard
product
b) do
not become hard with the application of heat and pressure and no chemical
change occurs
c) are
flexible and can withstand considerable wear under suitable conditions
d) are
used as a friction lining for clutches and brakes
55.
A
cotter joint is used to transmit
a) axial
tensile load only
b) axial
compressive load only
c) combined
axial and twisting loads
d) axial
tensile or compressive loads
56.
To
ensure self-locking in a screw jack, it is essential that the helix angle is
a) larger
than friction angle
b) smaller
than friction angle
c) equal
to friction angle
d) such
as to give maximum efficiency in lifting
57.
The
figure shows a clamp coupling. If the effective number of bolts in each shaft
is n/2, the allowable tensile stress for the bolt material is σt and
the root diameter of the bolt is dc, then the clamping pressure
between the shaft and the sleeve is
a) nπdc2σt/(dL)
b) nπdc2σt/(4dL)
c) 3nπdc2σt/(4dL)
58.
In
a typical clamp coupling the clamping pressure between the shaft and the sleeve
is given by
a) nπdc2σt/(dL)
b) 0.5nπdc3/2σt/(dL1/2)
c) 0.75nπdc4σt/(dL)2
d) 0.25nπdc2σt/(dL)
Where dc is the
core diameter of the bolts, d is the clamp diameter, L the clamp length and σt
is the tensile yield stress.
59.
In a disc clutch, maximum pressure occurs
a) at
the inner radius
b) at
the centre
c) at
the outer radius
60.
In which of the following, uniform pressure
theory is more approximate?
a) a
new clutch
b) an
old clutch
c) friction
clutch
61.
For a self-locking brake
a) A
large actuating force is needed
b) A
small actuating force is needed
c) No
actuating force is needed
62.
If
in the band brake shown below, drum diameter = 400mm, lining width = 75mm,
rotational speed is 200 rpm, a = 250mm, m = 75mm, α = 2700, μ = 0.2 and the
maximum lining pressure is 0.5 MPa, the torque is
a) 632
Nm
b) 915
Nm
c) 1150
Nm
d) 3160
Nm
63.
Hydrodynamic
Lubrication occurs at:
a) Very
low Sommerfeld Number
b) Low
Sommerfeld Number
c) Medium
Sommerfeld Number
d) High
Sommerfeld Number
64.
Hydrodynamic Lubrication occurs at:
a) At
zero Sommerfeld number
b) At
relatively low Sommerfeld number
c) At
relatively high Sommerfeld number
65.
Hydrodynamic
lubricated bearings are
a) Thick
film bearings
b) Thin
film bearings
c) Zero
film bearings
66.
When
a shaft rotates in anticlockwise direction at slow speed in a bearing, then it
will
a) have
contact at the lowest point of bearing
b) move
towards right of the bearing making metal to metal contact
c) move
towards left of the bearing making metal to metal contact
d) move
towards right of the bearing making no metal to metal contact
67.
If
Z = Absolute viscosity of the lubricant in kg/m-s, N = Speed of the journal in
rpm, and p = Bearing pressure in N/mm2, then the bearing
characteristic number is
a) ZN/p
b) Zp/N
c) Z/Pn
d) pN/Z
68.
A
ball bearing subjected to a radial load of 5 kN is expected to have a life of
8000 hours at 1450 rpm with a reliability of 99%. The dynamic load capacity of
the bearing so that it can be selected from the manufacturer's catalogue based
on a reliability of 90% is
a) 86.5
kN
b) 68.5
kN
c) 58.6
kN
d) 1
kN
69.
The
ball bearings are usually made from
a) low
carbon steel
b) medium
carbon steel
c) high
speed steel
d) chrome
nickel steel
70.
The
tapered roller bearings can take
a) radial
load only
b) axial
load only
c) both
radial and axial loads
71.
The
listed life of a rolling bearing, in a catalogue, is the
a) minimum
expected life
b) maximum
expected life
c) average
life
72.
Which
of the following are called as Anti-friction bearings?
a) Fluid
Film bearings
b) Rolling
contact bearings
c) Sliding
contact bearings
d) Journal
bearings
73.
The
load rating of a bearing is given for
a) Axial
loads only
b) Radial
loads only
c) Both
axial and radial loads
74.
If
two groups of identical ball bearings are tested under loads P1 and
P2 for respective lives of L1 and L2 , then L1/L2
is
a) (P1/P2)1/3
b) (P2/P1)1/3
c) (P1/P2)3
d) (P2/P1)3
75.
Which
of the following is best suitable for high speeds of shaft and high loads?
a) Journal
bearing
b) Ball
bearing
c) Roller
bearing
76.
Can
a block moving over a constant height fluid film carry load?
a) Yes
b) No
c) Depends
upon viscosity of the fluid
77.
If Sommerfeld number increases, then the Eccentricity
ratio
a) Increases
b) Decreases
c) Remains
same
78.
If Sommerfeld number increases, then the minimum
film thickness
a) Increases
b) Decreases
c) Remains
same
79.
If
Sommerfeld number increases, then the ratio of side flow to total flow
a) Decreases
b) Increases
c) Remains
same
80.
If
Sommerfeld number increases, then the coefficient of friction
a) Decreases
b) Increases
c) Remains
same
************* THE END *************
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