University Of Pune Question Paper
S.E. (Chemical) (Semester – II) Examination, 2011
PRINCIPLES OF DESIGN
(2003 Course)
Time : 3 Hours Max. Marks : 100
Instructions : 1) Answer 3 questions from Section I and 3 questions
from Section II.
2) Answers to the two Sections should be written in
separate books.
3) Neat diagrams must be drawn wherever necessary.
4) Black figures to the right indicate full marks.
5) Use of logarithmic tables, slide rule, Mollier charts,
electronic pocket calculator and steam tables is
allowed.
6) Assume suitable data, if necessary.
SECTION – I
1. a) Explain the nature of machine design problem. Also explain the process of
machine design. 6
b) An equilateral triangular bar of 15 mm side and 2.5 m long is found to contract
in length by 2 mm. Calculate the push on the bar if E = 2 × 105 MPa. 6
c) A mild steel flat 150 mm wide, 20 mm thick and 6 m long carries an axial
push of 200 KN. Find compressive stress and strain with E = 2 × 105 MPa. 6
OR
2. a) Classify machine designs based on :
i) Nature of new idea, and
ii) The method used. 6
b) A metal rod having 16 mm diameter fractured at a tensile force of 90 KN.
Another hollow circular rod of 25 mm id made of same metal has to withstand
a tensile force of 40 KN. Adopting a F.O.S. of 3, determine the required wall
thickness. 6
c) A tie bar 25 mm in diameter carries an axial force which causes stress of
120 MPa in it. It is attached to a rigid bracket by means of 4 bolts, each of which
can be stressed to 90 MPa. Find the suitable diameter for bolts. 6
3. a) A singly overhang beam ‘ABC’ is simply supported at ‘A’ and ‘B’ with
AB = 9 m and BC = 3 m. (‘C’ is free end). The beam carries u.v.l. on portion
‘AB’ with zero intensity at ‘A’ and
m
KN 6 load at ‘B’. The end ‘C’ carries
C.W. moment of 18 KN-m :
i) Draw SFD and BMD for the beam
ii) Find maximum sagging and hogging BM alongwith their positions
iii) Find the point of contraflexure if any. 8
b) At a point in a bracket, the stresses on two mutually perpendicular planes are
600 MPa (t) and 400 MPa (c) along with complementary shear stress of
100 MPa. Find using Mohr’s circle method :
i) The position of principal planes with respect to the plane carrying 600 MPa
stress.
ii) Magnitudes and nature of principal stresses.
iii) The position of plane carrying maximum shear stress and value of
maximum shear stress.
iv) The normal, tangential and resultant stress on the plane at 30° with plane
carrying 600 MPa stress. Also find angle of obliquity. 8
OR
4. a) A cantilever of 2 m span has central downward load of 4 KN, an upward
force of 1.5 KN at free end and U.D.L. of 1.5 KN / m between two point
loads.
i) Construct SFD and BMD for the beam.
ii) Find maximum sagging and hogging BM values along with their positions.
iii) Find point of contraflexure if any. 8
b) At a point in strained material, there are two planes at right angles to each
other on which normal stress intensities are 75 MPa (t) and 45 MPa (c)
accoMPanied by complimentary shear stress. ( τ ). The major principal stress
is 105 MPa (t). Find using Mohr’s circle method or otherwise :
i) Shearing stress ( τ ) and minor principal stress.
ii) Maximum shearing stress and the plane on which it acts.
iii) The normal, tangential and resultant stress on the plane at 35° with the plane
carrying 75 MPa. 8
5. a) A plate 75 mm wide and 12.5 mm thick is joined with another plate by a
single transverse weld and a double parallel fillet weld. Find the length of
weld if maximum tensile and shear stresses are 70 MPa and 56 MPa respectively. 6
b) i) Draw neat sketch of socket and spigot cotter joint showing all parts and
their dimensions. 2
ii) Design a cottered joint to resist safely a load of 40 KN that acts along the
coincident axes of the rods connected by the cotter. The material of the
cottert and rods will permit the stresses of 50 MPa in tension, 105 MPa in
compression and 40 MPa in shear. 8
OR
6. a) A plate 100 mm wide and 10 mm thick is to be welded with another plate by
means of transverse welds at the ends. If the plates are subjected to load of
70 KN, find the length of the weld for static as well as fatigue loading. Take
permissible shearing stress of 70 MPa and stress
concentration factor of 2.7. 6
b) i) Draw neat sketch of knuckle joint showing various parts along with their
dimensions. 2
ii) Design a knuckle joint for a tie rod of circular section to sustain a maximum
pull of 70 KN. The ultimate strength of rod in shear is 420 MPa, while that
for pin material is 510 MPa in tension and 396 MPa in shear. Taking
F.O.S. of 6, determine tie rod section and pin section. Also determine
other dimensions of the joint and check shear resistance of pin, tensile
resistance of rod end and forked end of the joint for safety. 8
SECTION – II
7. a) The shaft running at 120 rpm transmits 430 KW. The working conditions to
be satisfied by the shafts are :
i) The shear stress must not exceed 56 MPa
ii) The angle of twist must not be more than 1° in a length of 16 diameters.
Calculate the safe diameter of the shaft.
Take G = 0.85 × 105 MPa. 4
b) The shaft of uniform diameter is supported in bearings at ‘C’ and ‘D’ which
are 800 mm apart. The shaft carries pulleys ‘A’ and ‘B’ at the ends at distances
150 mm and 250 mm from ‘C’ and ‘D’ respectively. Pulley ‘A’ weighs 200 N,
which carries belt with tight side tension 2 KN while pulley ‘B’ weighs 400 N
with tight side tension 900 N. The shaft transmits 7.5 KW at 400 rpm. Estimate
a suitable shaft diameter for the shaft, adopting a working shear stress of
40 MPa (Use maximum shear stress theory of elastic failure). 6
c) A muff coupling is used to connect two steel shafts of 55 mm diameter,
transmitting 40 KW at 350 rpm. The allowable shear and crushing stresses
for shaft and key material are 40 MPa and 80 MPa respectively, while the
sleeve material has shear stress of 15 MPa. Design suitable key and sleeve
based on safety in crushing and shearing. 6
OR
8. a) Three pulleys ‘A’, ‘B’ and ‘C’ are mounted on a shaft and are at distances of
1200 mm, 2100 mm and 2700 mm respectively from the left hand bearing.
The bearings are 3600 mm apart. Pulley ‘A’ is 500 mm, ‘B’ 750 mm and ‘C’
375 mm in diameter. A power unit supplies 15 KW to ‘A’ and machinery
takes 9 KW from ‘B’ and 6 KW from ‘C’. A horizontal drive is arranged to
‘A’, while the drive ‘B’ has to be vertically downwards. The drive from ‘C’
is taken off at 45° to drive ‘A’ and in a downward direction. The speed of the
shaft is 200 rpm and the allowable shear stress in the shaft is 32 MPa. The
angle of lap of belt on pulley is 180° in each case, and the coefficient of
friction between belt and pulley is 0.32. Obtain the shaft diameter. 12
b) Draw neat sketch of bushed pin type flexible coupling. 4
9. a) A leather belt 9 mm × 250 mm is used to drive a cast iron pulley 900 mm in
diameter at 336 rpm. If the active arc on the smaller pulley is 120° and the
stress in tight side is 2 N / mm2, find the power capacity of the belt. The
density of leather is 980 kg / m3 and coefficient of friction of leather on cast
iron is 0.35. 8
b) The load on journal bearing is 150 KN due to turbine shaft of 300 mm
diameter running at 1800 rpm. Determine :
i) Length of the bearing if the allowable bearing pressure is 1.6 N / mm2 and
ii) Amount of heat to be removed by the lubricant per minute if the bearing
temperature is 60° C and viscosity of oil at 60° C is 0.02 kg / m-s and the
bearing clearance is 0.25 mm. Take K = 0.002. 8
OR
10. a) A compressor, requiring 90 KW, is to run at about 250 rpm. The drive is by
V-belts from an electric motor running at 750 rpm. The diameter of the
pulley on the compressor shaft must not be greater than 1 m while the centre
distance between the pulleys is limited to 1.75 m. The belt speed should not
exceed 1600 m / min. Determine the number of V belts required to transmit
the power if each belt has a cross-sectional area of 375 mm2 and the angle of
pulley is 35°. The coefficient of friction between the belt and the pulley is
0.25. Calculate the length required for each belt. 10
b) A journal bearing 60 mm in diameter and 90 mm long runs at 450 rpm. The
oil used for hydrodynamic lubrication has absolute viscosity of 0.06 kg / ms.
If the diametral clearance is 0.1 mm, find the safe load on the bearing.
Take Sommerfield number = 14.3 × 106. 6
11. Write short notes on : 18
a) Globe valve
b) Steam trap
c) Centrifugal pump.
OR
12. Write short notes on : 18
a) 3-way valve
b) Diaphragm valve
c) Fans and blowers.
————————
S.E. (Chemical) (Semester – II) Examination, 2011
PRINCIPLES OF DESIGN
(2003 Course)
Time : 3 Hours Max. Marks : 100
Instructions : 1) Answer 3 questions from Section I and 3 questions
from Section II.
2) Answers to the two Sections should be written in
separate books.
3) Neat diagrams must be drawn wherever necessary.
4) Black figures to the right indicate full marks.
5) Use of logarithmic tables, slide rule, Mollier charts,
electronic pocket calculator and steam tables is
allowed.
6) Assume suitable data, if necessary.
SECTION – I
1. a) Explain the nature of machine design problem. Also explain the process of
machine design. 6
b) An equilateral triangular bar of 15 mm side and 2.5 m long is found to contract
in length by 2 mm. Calculate the push on the bar if E = 2 × 105 MPa. 6
c) A mild steel flat 150 mm wide, 20 mm thick and 6 m long carries an axial
push of 200 KN. Find compressive stress and strain with E = 2 × 105 MPa. 6
OR
2. a) Classify machine designs based on :
i) Nature of new idea, and
ii) The method used. 6
b) A metal rod having 16 mm diameter fractured at a tensile force of 90 KN.
Another hollow circular rod of 25 mm id made of same metal has to withstand
a tensile force of 40 KN. Adopting a F.O.S. of 3, determine the required wall
thickness. 6
c) A tie bar 25 mm in diameter carries an axial force which causes stress of
120 MPa in it. It is attached to a rigid bracket by means of 4 bolts, each of which
can be stressed to 90 MPa. Find the suitable diameter for bolts. 6
3. a) A singly overhang beam ‘ABC’ is simply supported at ‘A’ and ‘B’ with
AB = 9 m and BC = 3 m. (‘C’ is free end). The beam carries u.v.l. on portion
‘AB’ with zero intensity at ‘A’ and
m
KN 6 load at ‘B’. The end ‘C’ carries
C.W. moment of 18 KN-m :
i) Draw SFD and BMD for the beam
ii) Find maximum sagging and hogging BM alongwith their positions
iii) Find the point of contraflexure if any. 8
b) At a point in a bracket, the stresses on two mutually perpendicular planes are
600 MPa (t) and 400 MPa (c) along with complementary shear stress of
100 MPa. Find using Mohr’s circle method :
i) The position of principal planes with respect to the plane carrying 600 MPa
stress.
ii) Magnitudes and nature of principal stresses.
iii) The position of plane carrying maximum shear stress and value of
maximum shear stress.
iv) The normal, tangential and resultant stress on the plane at 30° with plane
carrying 600 MPa stress. Also find angle of obliquity. 8
OR
4. a) A cantilever of 2 m span has central downward load of 4 KN, an upward
force of 1.5 KN at free end and U.D.L. of 1.5 KN / m between two point
loads.
i) Construct SFD and BMD for the beam.
ii) Find maximum sagging and hogging BM values along with their positions.
iii) Find point of contraflexure if any. 8
b) At a point in strained material, there are two planes at right angles to each
other on which normal stress intensities are 75 MPa (t) and 45 MPa (c)
accoMPanied by complimentary shear stress. ( τ ). The major principal stress
is 105 MPa (t). Find using Mohr’s circle method or otherwise :
i) Shearing stress ( τ ) and minor principal stress.
ii) Maximum shearing stress and the plane on which it acts.
iii) The normal, tangential and resultant stress on the plane at 35° with the plane
carrying 75 MPa. 8
5. a) A plate 75 mm wide and 12.5 mm thick is joined with another plate by a
single transverse weld and a double parallel fillet weld. Find the length of
weld if maximum tensile and shear stresses are 70 MPa and 56 MPa respectively. 6
b) i) Draw neat sketch of socket and spigot cotter joint showing all parts and
their dimensions. 2
ii) Design a cottered joint to resist safely a load of 40 KN that acts along the
coincident axes of the rods connected by the cotter. The material of the
cottert and rods will permit the stresses of 50 MPa in tension, 105 MPa in
compression and 40 MPa in shear. 8
OR
6. a) A plate 100 mm wide and 10 mm thick is to be welded with another plate by
means of transverse welds at the ends. If the plates are subjected to load of
70 KN, find the length of the weld for static as well as fatigue loading. Take
permissible shearing stress of 70 MPa and stress
concentration factor of 2.7. 6
b) i) Draw neat sketch of knuckle joint showing various parts along with their
dimensions. 2
ii) Design a knuckle joint for a tie rod of circular section to sustain a maximum
pull of 70 KN. The ultimate strength of rod in shear is 420 MPa, while that
for pin material is 510 MPa in tension and 396 MPa in shear. Taking
F.O.S. of 6, determine tie rod section and pin section. Also determine
other dimensions of the joint and check shear resistance of pin, tensile
resistance of rod end and forked end of the joint for safety. 8
SECTION – II
7. a) The shaft running at 120 rpm transmits 430 KW. The working conditions to
be satisfied by the shafts are :
i) The shear stress must not exceed 56 MPa
ii) The angle of twist must not be more than 1° in a length of 16 diameters.
Calculate the safe diameter of the shaft.
Take G = 0.85 × 105 MPa. 4
b) The shaft of uniform diameter is supported in bearings at ‘C’ and ‘D’ which
are 800 mm apart. The shaft carries pulleys ‘A’ and ‘B’ at the ends at distances
150 mm and 250 mm from ‘C’ and ‘D’ respectively. Pulley ‘A’ weighs 200 N,
which carries belt with tight side tension 2 KN while pulley ‘B’ weighs 400 N
with tight side tension 900 N. The shaft transmits 7.5 KW at 400 rpm. Estimate
a suitable shaft diameter for the shaft, adopting a working shear stress of
40 MPa (Use maximum shear stress theory of elastic failure). 6
c) A muff coupling is used to connect two steel shafts of 55 mm diameter,
transmitting 40 KW at 350 rpm. The allowable shear and crushing stresses
for shaft and key material are 40 MPa and 80 MPa respectively, while the
sleeve material has shear stress of 15 MPa. Design suitable key and sleeve
based on safety in crushing and shearing. 6
OR
8. a) Three pulleys ‘A’, ‘B’ and ‘C’ are mounted on a shaft and are at distances of
1200 mm, 2100 mm and 2700 mm respectively from the left hand bearing.
The bearings are 3600 mm apart. Pulley ‘A’ is 500 mm, ‘B’ 750 mm and ‘C’
375 mm in diameter. A power unit supplies 15 KW to ‘A’ and machinery
takes 9 KW from ‘B’ and 6 KW from ‘C’. A horizontal drive is arranged to
‘A’, while the drive ‘B’ has to be vertically downwards. The drive from ‘C’
is taken off at 45° to drive ‘A’ and in a downward direction. The speed of the
shaft is 200 rpm and the allowable shear stress in the shaft is 32 MPa. The
angle of lap of belt on pulley is 180° in each case, and the coefficient of
friction between belt and pulley is 0.32. Obtain the shaft diameter. 12
b) Draw neat sketch of bushed pin type flexible coupling. 4
9. a) A leather belt 9 mm × 250 mm is used to drive a cast iron pulley 900 mm in
diameter at 336 rpm. If the active arc on the smaller pulley is 120° and the
stress in tight side is 2 N / mm2, find the power capacity of the belt. The
density of leather is 980 kg / m3 and coefficient of friction of leather on cast
iron is 0.35. 8
b) The load on journal bearing is 150 KN due to turbine shaft of 300 mm
diameter running at 1800 rpm. Determine :
i) Length of the bearing if the allowable bearing pressure is 1.6 N / mm2 and
ii) Amount of heat to be removed by the lubricant per minute if the bearing
temperature is 60° C and viscosity of oil at 60° C is 0.02 kg / m-s and the
bearing clearance is 0.25 mm. Take K = 0.002. 8
OR
10. a) A compressor, requiring 90 KW, is to run at about 250 rpm. The drive is by
V-belts from an electric motor running at 750 rpm. The diameter of the
pulley on the compressor shaft must not be greater than 1 m while the centre
distance between the pulleys is limited to 1.75 m. The belt speed should not
exceed 1600 m / min. Determine the number of V belts required to transmit
the power if each belt has a cross-sectional area of 375 mm2 and the angle of
pulley is 35°. The coefficient of friction between the belt and the pulley is
0.25. Calculate the length required for each belt. 10
b) A journal bearing 60 mm in diameter and 90 mm long runs at 450 rpm. The
oil used for hydrodynamic lubrication has absolute viscosity of 0.06 kg / ms.
If the diametral clearance is 0.1 mm, find the safe load on the bearing.
Take Sommerfield number = 14.3 × 106. 6
11. Write short notes on : 18
a) Globe valve
b) Steam trap
c) Centrifugal pump.
OR
12. Write short notes on : 18
a) 3-way valve
b) Diaphragm valve
c) Fans and blowers.
————————
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