JNTU Kakinada B-Tech 3-1 RT31033 I DESIGN OF MACHINE MEMBERS – I R13 April 2018 Question Paper

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Code No: RT31033
III B. Tech I Semester Supplementary Examinations, May – 2018
DESIGN OF MACHINE MEMBERS ? I (Mechanical Engineering)Time: 3 hours Max. Marks: 70
Note: 1. Question Paper consists of two parts (Part-A and Part-B) 2. Answering the question in Part-A is compulsory
3. Answer any THREE Questions from Part-B
(Data books may be allowed)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PART ?A
1 a) Write about preferred numbers? [3M]
b) How will you reduce stress concentration in shaft with keyway? [4M]
c) Write the advantages and limitations of bolted joints? [4M]
d) Write the applications of spigot and socket joint? [4M]
e) What is the importance of split muff couplings? [3M]
f) List the classification of springs? [4M]
PART -B
2 a) Explain the manufacturing considerations in design? [8M]
b) How do you understand failure? Explain the various theories of failure?
[8M]
3 a) A torsion bar spring has a solid round 20 mm diameter section which blends
smoothly at each end with a larger splined section. It is subjected to a completely
reversed nominal torsional stress of 210 MN/m
2
. Stress concentration is
negligible, and the surfaces are machined. Estimate the fatigue life corresponding
to each of the following materials :
i) steel= 250 HB,
ii) Cast iron Su= 350 MN/m
2
.
[12M]
b) Describe the estimation of endurance strength?
[4M]
4 a) How is the allowable stress calculated for a riveted joint subjected to alternating
type of load?
[6M]
b) The end of a receiver, cylindrical in shape is closed by a lap joint using rivets.
The maximum pressure in the receiver is 1 MPa. The axial length of the
receiver is limited to 2 m while its storing capacity is 2 m
3
. Design the suitable
lap joint giving a neat sketch. The permissible stresses in shear and crushing
of rivets may be taken as 30 MPa and 70 MPa. The permissible tensile stress
for the plate material is 80 MPa.

1 of 2

[10M]
R13
SET – 1
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Code No: RT31033
III B. Tech I Semester Supplementary Examinations, May – 2018
DESIGN OF MACHINE MEMBERS ? I (Mechanical Engineering)Time: 3 hours Max. Marks: 70
Note: 1. Question Paper consists of two parts (Part-A and Part-B) 2. Answering the question in Part-A is compulsory
3. Answer any THREE Questions from Part-B
(Data books may be allowed)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PART ?A
1 a) Write about preferred numbers? [3M]
b) How will you reduce stress concentration in shaft with keyway? [4M]
c) Write the advantages and limitations of bolted joints? [4M]
d) Write the applications of spigot and socket joint? [4M]
e) What is the importance of split muff couplings? [3M]
f) List the classification of springs? [4M]
PART -B
2 a) Explain the manufacturing considerations in design? [8M]
b) How do you understand failure? Explain the various theories of failure?
[8M]
3 a) A torsion bar spring has a solid round 20 mm diameter section which blends
smoothly at each end with a larger splined section. It is subjected to a completely
reversed nominal torsional stress of 210 MN/m
2
. Stress concentration is
negligible, and the surfaces are machined. Estimate the fatigue life corresponding
to each of the following materials :
i) steel= 250 HB,
ii) Cast iron Su= 350 MN/m
2
.
[12M]
b) Describe the estimation of endurance strength?
[4M]
4 a) How is the allowable stress calculated for a riveted joint subjected to alternating
type of load?
[6M]
b) The end of a receiver, cylindrical in shape is closed by a lap joint using rivets.
The maximum pressure in the receiver is 1 MPa. The axial length of the
receiver is limited to 2 m while its storing capacity is 2 m
3
. Design the suitable
lap joint giving a neat sketch. The permissible stresses in shear and crushing
of rivets may be taken as 30 MPa and 70 MPa. The permissible tensile stress
for the plate material is 80 MPa.

1 of 2

[10M]
R13
SET – 1
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Code No: RT31033

5 a) A machinery shaft supported on a bearing 2.4 metre apart is to transmit
187.5 kW at 200 rev/min. It is subjected to a bending load of 5000 N located
at a distance of 0.66 metre from one bearing. Safe stress in shear is 42 MPa
and in bending 84 MPa. i.) Determine the shaft diameter for steady loading
ii.) Determine the shaft diameter if the transverse load is steady and the
torsional load is suddenly applied.
[12M]
b) Write the importance and applications of jib and cotter joints?
[4M]
6 A propeller shaft is made-up by joining together number of solid shafts. The joint
is made by forging the ends of the shaft in the form of a flange, and bolting the
flanges together by means of 8 bolts. If the shaft transmits 60kW at 120 rpm,
determine the size of the shaft, the diameter and thickness of the flange and the
diameter and pitch circle diameter of bolts. Permissible stresses are t = 35MPa ;
sc = 45MPa.
[16M]
7 A rail carriage weighing 200kN and running at 5 km/hour is brought to rest by
four buffer springs of close coiled helical type during connection with another
carriage which is already at rest. The mean coil diameter is 5 times the wire
diameter. The deflection of each spring is 220 mm, to bring the carriage to
rest. Safe shear stress for the spring material is 400 N/mm
2
. Calculate the
maximum load on the spring, diameter of wire and coil, number of turns and
free length of spring. Assume the ends of spring are squared and ground. Take
G= 0.8?10
4
N/mm
2
.
[16M

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