MACHINE DESIGN

V Semester
Diploma Examination 

MACHINE
DESIGN 

Time: 3
Hours] 
Note:
Answer all questions 
[Max Marks:
100 

PARTA 

1 
List the general Considerations in machine design 
5 

2 
Explain manmachine joint system 
5 

3 
List with examples five basic forms for shape of product 
5 


PARTB 


4 a 
List the different types of riveted joints and rivets. 
5 

B 
Two plates of 10 mm thickness each are to be joined by means of a
single 



riveted
double strap butt joint.
Determine the rivet diameter; rivet pitch, 
15 


strap thickness and efficiency of the joint. Take the working
stresses in 



tension and shearing as 80 MPa and 60 MPa respectively. 



OR 


4 a b 
Discuss the stresses induced in the Screw
fasteners when it is subjected to static loading. The cylinder head of a
steam engine is subjected to a steam pressure of 0.7 N/mm2. It is held in
position by means of 12 bolts. A soft copper gasket is 
5 15 


used to make the joint leakproof. The effective diameter of cylinder
is 



300 mm. Find the size of the bolts so that the stress in the bolts is
not to 



exceed 100 MPa. 


5 a 
Explain the effect of keyway cut into the
shaft. Select the diameter of a solid steel shaft to transmit 20kw
at 200 rpm. The ultimate shear stress for the steel may be taken as 360mpa
and factor of safety as 8. If a hallow shaft is to be used in place of solid
shaft , finds the inside and outside diameter when the ratio of inside to
outside is 0.5. OR Explain how the shafts are designed when it is subjected to twisting
moment only on stiffness/strength basis. Select the diameter of a solid steel shaft for a pair of wheels of a
railway wagon carries a load of 50KN on each axle box acting at a distance of
100mm outside the wheel base. The gauge of the rails is 1.4 m ,if the stress is not to exceed 100Mpa. 
5 

b 



15 

5 a b 
5 


15 

6 a 
Explain the applications of spring Design a
close coiled helical compression spring for a service load ranging from 2250
N to 2750 N. The axial deflection of the spring for the load range is 6 mm.
Assume a spring index of 5. The permissible shear stress intensity is 420 MPa
and modulus of rigidity, G = 84 kN/mm2. Neglect the effect of stress concentration. OR Classify the springs. 
5 

b 



15 

6 a 
5 



Design the spring for the buffers of a rail
wagon of mass 20 tonnes is 
8 

b 
moving with
a velocity of 2 m/s. It is brought to rest by two buffers with springs of 300
mm diameter. The maximum deflection of springs is 250 mm. The allowable shear stress in the spring material is 600 MPa. 
15 
PART
C 

7 
Design a
knuckle joint to connect two mild steel bars under a tensile load of 25 kN.
The allowable stresses are 65 MPa in tension, 50 MPa in shear and 83 MPa in
crushing. . OR Design a rigid flange coupling to transmit a the torque of 250 Nm between two coaxial shafts. The shaft is made of alloy steel, flanges out of cast iron and bolts out of steel. Four bolts are used to couple the flanges. The shafts are keyed to the flange hub. The
permissible stresses are given below: Shear stress on shaft =100 MPa Bearing or crushing stress
on shaft =250 MPa Shear stress on keys =100
MPa Bearing stress on keys
=250 MPa Shearing stress on cast iron =200 MPa Shear stress on bolts =100 MPa 
25 
8 
25 
V Semester Diploma Examination
MACHINE DESIGN
Note: The paper setter is of liberty to set the
questions on his/her desecration based on cognitive levels notified for that
unit. They have to follow only blue print of SEE question paper format. The
model question bank is only for reference to students/course coordinator to
initiate the process of teachinglearning only.
1)
Define machine Design.
2) List out the classification
of machine design.
3) List general considerations in machine
design.
4) Define the following terms
a) Load b) Stress c) strain
6) Define factor of safety.
7) Recall the equation for
bending.
8) Recall the equation for Torsion.
9) List the various factors to
be considered in deciding the factor of safety.
10) Label the salient features
of stress strain diagram for mild steel.
11) List the different types of
failure theories.
1.
Define fastener.
2.
Define Riveted joint.
3.
List the different types of riveted joints and rivets.
4.
Define efficiency of riveted joint.
1. Classify the fasteners.
2. Compare Bolt, stud and Nut.
3. Explain bolt of uniform
strength. Where it is preferably used.
4. Explain the stresses induced
in the Screw fasteners when it is subjected to static loading.
5. Interpret the reasons for
“Initial tightening of bolts is essential”.
6.
Interpret the reasons for “Excessive tightening of bolts is avoided”.
7. Explain the necessity of
riveted joint.
8. List the applications of
riveted joint in modern equipments.
9.
Explain the types of failures in riveted joint with sketch.
1.
A steam engine cylinder has an effective diameter of
350 mm and the maximum steam pressure acting on the cylinder cover is 1.25
N/mm2. Calculate the number and size of studs required to fix the cylinder
cover, assuming the permissible stress in the studs as 33 MPa.
2.
A mild steel cover plate is to be designed for an inspection hole in
the shell of a pressure vessel. The hole is 120 mm in diameter and the pressure
inside the vessel is 6 N/mm2. Design the cover plate along with the bolts.
Assume allowable tensile stress for mild steel as 60 MPa and for bolt material
as 40 MPa.
3.
The cylinder head of a steam engine is subjected to a steam pressure of
0.7 N/mm2. It is held in position by
means of 12 bolts. A soft copper gasket is used to make the joint leak proof.
The effective diameter of cylinder is 300 mm. Find the size of the bolts so
that the stress in the bolts is not to exceed 100 MPa.
4.
An eye bolt is to be used for lifting a load of 60 kN. Find the nominal
diameter of the bolt, if the tensile stress is not to exceed 100 MPa. Assume
coarse threads.
5.
Determine the safe tensile load for bolts of M 20 and M
36. Assume that the bolts are not initially
stressed and take the safe tensile stress as 200 MPa.
6.
An eye bolt carries a tensile load of 20 kN. Find the size of the bolt,
if the tensile stress is not to exceed 100 MPa..
7.
An engine cylinder is 300 mm in diameter and the steam pressure is 0.7
N/mm2. If the cylinder head is held
by 12 studs, find the size. Assume safe tensile stress as 28 MPa.
1. A double riveted lap joint
with zigzag riveting is to be designed for 13 mm thick plates. Assume σt = 80
MPa ; τ = 60 MPa ; and σc = 120 MPa. State how the joint will fail and find the
efficiency of the joint.
2. Two plates of 10 mm thickness
each are to be joined by means of a single riveted double strap butt joint.
Determine the rivet diameter; rivet pitch, strap thickness and efficiency of
the joint. Take the working stresses in tension and shearing as 80 MPa and 60
MPa respectively.
3. Design a double riveted butt
joint with two cover plates for the longitudinal seam of a boiler shell 1.5 m
in diameter subjected to a steam pressure of 0.95 N/mm2. Assume joint
efficiency as 75%, allowable tensile
stress in the plate 90 MPa ; compressive stress 140 MPa
; and shear
stress in the rivet 56 MPa.
4. A single riveted lap joint
is made in 15 mm thick plates with 20 mm diameter rivets. Determine the
strength of the joint, if the pitch of rivets is 60 mm. Take σt = 120 MPa; τ =
90 MPa and σc = 160 MPa.
5. Two plates 16 mm thick are
joined by a double riveted lap joint. The pitch of each row of rivets is 90mm.
The rivets are 25 mm in diameter. The permissible stresses are as +follows: σt
= 140 MPa ; τ = 110 MPa and σc = 240 MPa Find the efficiency of the joint.
6. A single riveted double
cover butt joint is made in 10 mm thick plates with 20 mm diameter rivets
with a pitch of
60 mm. Calculate the efficiency of the joint, if σt = 100 MPa ; τ = 80 MPa and
σc = 160 MPa.
7. A double riveted double
cover butt joint is made in 12 mm thick plates with 18 mm diameter rivets. Find
the efficiency of the joint for a pitch of 80 mm, if σt = 115 MPa ; τ = 80 MPa
and σc = 160 MPa.
1)
Explain the effect of keyway cut into the shaft.
2) List the reasons for
rectangular keys are preferred over square keys.
3) Explain how
the shafts are designed when it is subjected to twisting moment only on
stiffness/strength basis.
4) Explain how
the shafts are designed when it is subjected to Bending moment only on
stiffness/strength basis.
5) Explain how
the shafts are designed when it is subjected to combined twisting moment and
bending moment on stiffness/strength basis.
6)
List the properties of materials used for shafts.
7) Classify Sunk keys.
8) List he standard sizes of
Transmission shafts.
9) Explain how the shafts are
designed on Rigidity basis.
1) Select the
diameter of the shaft for a mild steel rotating at 200 rpm, transmiting 20kW with a allowable shear stress of 42MPa.
2) Select the
diameter of the shaft for a mild steel rotating at 240rpm, is transmitting 1 MW
The maximum torque transmitted exceeds the mean torque by 20%. The allowable
shear stress as 60mpa.
3) Select the
diameter of a solid steel shaft to transmit 20kw at 200 rpm. The ultimate shear
stress for the steel may be taken as 360mpa and factor of safety as 8. If a
hallow shaft is to be used in place of solid shaft , finds the
inside and outside diameter when the ratio of inside to outside is 0.5.
4) Select the
diameter of a solid steel shaft for a pair of wheels of a railway wagon carries
a load of 50KN on each axle box acting at a distance of 100mm outside the wheel
base. The gauge of the rails is 1.4 m ,if the stress is not to exceed 100Mpa.
5) Select the
diameter of a solid steel shaft is subjected to bending moment of 3000Nm
and a torque of 10000Nm. The shaft is
made of 45 c 8 steel having ultimate tensile stress of 700Mpa and Ultimate
shear stress of 500Mpa. Assuming factor of safety as 6.
6) Select the diameter of a solid
steel shaft made of mild steel is required to transmit 100 kW at 300 r.p.m. The
supported length of the shaft is 3 metres. It
carries two pulleys each weighing 1500 N supported at a distance of 1
metre from the ends respectively. Assuming the safe value of stresses
7) Select the diameter of a
solid steel shaft by considering two different theories of failure made of
steel of yield strength 700 MPa is subjected to static loads consisting of a
bending moment of 10 kNm and a torsional moment of 30 kNm. and assuming a
factor of safety of 2.
8) Choose the outside and inside diameter
of a hollow steel shaft transmits 600 kW at 500
r.p.m. The
maximum shear stress is 62.4 MPa. The outer diameter is twice of inside
diameter, assuming that the maximum torque is 20% greater than the mean torque.
1)
Recommend the rectangular key for a shaft of 50 mm diameter. The
shearing and
crushing stresses for the key
material are 42 MPa and 70 MPa.
2) Recommend the required
length of key, if the shaft is loaded to transmit the maximum permissible
torque. Use maximum shear stress theory and assume a factor of safety of 2 for
a 45 mm diameter shaft is made of steel with a yield strength of 400 MPa. A
parallel key of size 14 mm wide and 9 mm thick made of steel with a yield
strength of 340 MPa is to be used.
3) A 15 kW, 960 r.p.m. motor
has a mild steel shaft of 40 mm diameter and the extension being 75 mm. The
permissible shear and crushing stresses for the mild steel key are 56 MPa and
112 MPa. Design the keyway in the motor shaft extension. Check the shear
strength of the key against the normal strength of the shaft.
4) Select the length of a 20 mm
wide key required to mount a pulley on the shaft so that the stress in the key
does not exceed 42MPa. A shaft 80 mm diameter transmits power at maximum shear
stress of 63 MPa.
5) Select the dimensions of the
key so that A shaft 30 mm diameter is transmitting power at a maximum shear
stress of 80 MPa. If a pulley is
connected to the shaft by means of a key, the stress in the key is not to
exceed 50 MPa and length of the key is 4
times the width.
6) Select a suitable key for
the gear having a steel shaft has a diameter of 25 mm. The shaft rotates at a
speed of 600 r.p.m. and transmits 30 kW through a gear. The tensile and yield
strength of the material of shaft are 650 MPa and 353 MPa respectively. Take a
factor of safety 3. Assume that the
key and shaft are made of the same material.
Apply/ Analysis
Muff
coupling
1) Design a
muff coupling which is used to connect two steel shafts transmitting 40 kW at
350 r.p.m. The material for the shafts and key is plain carbon steel for which
allowable shear and crushing stresses may be taken as 40 MPa and 80 MPa
respectively. The material for the muff is cast iron for which the allowable
shear stress may be assumed as 15 MPa.
2) Design a
muff coupling to connect two shafts transmitting 40 kW at 120 r.p.m. The
permissible shear and crushing stress for the shaft and key material (mild
steel) are 30 MPa and 80 MPa respectively. The material of muff is cast iron
with permissible shear stress of 15 MPa. Assume that the maximum torque
transmitted is 25 per cent greater than the mean torque.
1) Design a cast iron
protective type flange coupling to transmit 15 kW at 900
r.p.m. from an electric motor to a
compressor. The service factor may be assumed as 1.35. The
Following permissible stresses
may be used :
Shear stress for shaft, bolt and
key material = 40 MPa Crushing stress for bolt and key = 80 MPa
Shear stress for cast iron = 8
MPa
2) Design a protective type of
cast iron flange coupling for a steel shaft
transmitting 15
kW at 200 r.p.m. and having an allowable shear stress of 40 MPa. The working
stress in the bolts should not exceed 30 MPa. Assume that the same material is
used for shaft and key and that the crushing stress is twice the value of its
shear stress. The maximum torque is 25% greater than the full load torque. The
shear stress for cast iron is 14 MPa.
3) Design a cast iron flange
coupling for a mild steel shaft transmitting 90 kW at 250 r.p.m. The allowable
shear stress in the shaft is 40 MPa and the angle of twist is not to exceed 1°
in a length of 20 diameters. The allowable shear stress in the coupling bolts
is 30 MPa.
4)
Design a rigid flange coupling to transmit a torque of
250 Nm between two coaxial shafts. The shaft is made of alloy steel, flanges
out of cast iron and bolts out of steel. Four bolts are used to couple the
flanges. The shafts are keyed to the flange hub. The permissible stresses are
given below:
Shear stress on shaft =100 MPa
Bearing or crushing stress on shaft
=250 MPa Shear stress on keys =100 MPa
Bearing stress on keys =250 MPa
Shearing stress on cast iron =200 MPa Shear stress on bolts =100 MPa
5) Two 35 mm shafts are connected by a flanged coupling. The flanges are
fitted with 6 bolts on 125 mm bolt circle. The shafts transmit a torque of 800
Nm at 350 r.p.m. For the safe stresses mentioned below, calculate 1. diameter
of bolts ; 2. thickness of flanges ; 3. key dimensions ;4. hub length; and 5.
power transmitted.
Safe shear stress for shaft
material = 63 MPa Safe stress for bolt material = 56 MPa
Safe stress for
cast iron coupling = 10 MPa Safe stress for key material = 46 MPa
1.
Design a cotter joint to connect two
mild steel rods for a pull of 30 kN. The maximum permissible stresses are 55
MPa in tension; 40 MPa in shear and 70 MPa in crushing. Draw a neat
sketch of the joint designed.
2.
Two rod ends of a pump are joined by means of a cotter
and spigot and socket at the ends. Design the joint for an axial load of 100 kN
which alternately changes from tensile to compressive. The allowable stresses for
the material used are 50 MPa in tension, 40 MPa in shear and 100 MPa in crushing.
3. Two mild steel
rods 40 mm diameter are to be
connected by a cotter joint. The
thickness of the cotter is 12 mm. Calculate the dimensions of the joint, if the
maximum permissible stresses are: 46 MPa in tension ; 35 MPa in shear and 70
MPa in crushing.
4. Design a
cotter joint to support a load varying from 30 kN in compression to 30 kN in
tension. The material used is carbon steel for which the following allowable
stresses may be used. The load is applied statically. Tensile stress =
compressive stress 50 MPa ; shear stress 35 MPa and crushing stress= 90 MPa.
1. Design
a knuckle joint to transmit 150 kN. The design stresses may be taken as 75 MPa in
tension, 60 MPa in shear and 150 MPa in compression.
2. Design a
knuckle joint for a tie rod of a circular section to sustain a maximum pull of
70 kN. The ultimate strength of the material of the rod against tearing is 420
MPa. The ultimate tensile and shearing strength of the pin material are 510 MPa
and 396 MPa respectively. Determine the tie rod section and pin section. Take
factor of safety = 6.
3. Design a
knuckle joint to connect two mild steel bars under a tensile load of 25 kN. The
allowable stresses are 65 MPa in tension, 50 MPa in shear and 83 MPa in crushing.
4. A knuckle
joint is required to withstand a tensile load of 25 kN. Design the joint if the
permissible stresses are :σt = 56 MPa ; τ = 40 MPa and σc = 70 MPa.
Remember
1)
List the applications of spring
3) List materials
used in Springs.
4) Define the
terms used in springs.
5) Name the
springs used in a) Spring balance b)Ball Pen c) Door Hinges d) Truck Chassis
e)Clock
Understand
1) Classify the springs.
2) Explain the
significance of Whal’s factor
3) Expline the
applications of spring
4) List the
materials used in Springs.
Problems on springs
Apply/ Analysis
1)
Design a close coiled helical compression spring for a
service load ranging from 2250 N to 2750 N. The axial deflection of the spring
for the load range is 6 mm. Assume a spring index of 5. The permissible shear
stress intensity is 420 MPa and the modulus of rigidity, G = 84 kN/mm2. Neglect the
effect of stress concentration.
2) Design and
draw a valve spring of a petrol engine for the following operating conditions:
Spring load when the valve is open = 400 N
Spring
load when the valve is closed = 250 N Maximum inside diameter of spring = 25 mm
Length of the spring when the valve is open= 40 mm
Length
of the spring when the valve is closed= 50 mm Maximum permissible shear stress
= 400 MPa
3)
Design the spring for the buffers of a rail wagon of mass
20 tonnes is moving with a velocity of 2 m/s. It is brought to rest by two
buffers with springs of 300 mm diameter. The
maximum
deflection of springs is 250 mm. The allowable shear stress in the spring
material is 600 MPa.
4)
Design a helical compression spring for a maximum load of
1000 N for a deflection of 25 mm using the value of spring index as 5. The
maximum permissible shear stress for spring wire is 420 MPa and modulus of
rigidity is 84 kN/mm2,with considering whal’s
factor.
Remember
1)
Define Ergonomics.
2)
List with examples five basic forms for the shape of the Product.
3)
List the types of controls.
4)
List the types of Display.
Understand
1)
Explain the relationship between functional
requirements and the external appearance of the Product.
2)
Explain the scope of ergonomics in product design.
3) Explain the meaning of
different colors as per the morgan’s code.
4) Explain the manmachine joint system.
5) Explain the ergonomics
considerations in the design of controls.
6) Explain the ergonomics
considerations in the design of the Display.