RTU 2016 Question Paper Semester IV Automobile Engineering Design of Machine Elements I

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t{ B.Tech. IV'Sem (Main & Back) Examl June-July 2016
srII Automobile Engineering
4AE4A Design of Machine Elements-I
+ AE, ME, PI

Time: 3 Hours Maximum Marks: 80
Min. Passing Marks (Main & Back): 26
Min. Passing Marks (Old Back): 24
Instructions to Candidates : -

Attempt any five questions, selecting one question from each unit. All
Questions carry equal marks. Schematic diagrams
must be shown
wherever necessary. Any data you feel missing suitably be assumed and
stated clearly.
Units of quantities used/ calculated must be stated clearly.

tlse of foltowing supporting material is permitted during examination'
(Mentioned in form No.205)

l. Desien Data Book-

UNIT.I
e.1 (a) What is standardization? What are the advantages of standardization? [3+3=6]
(b) Explain in detail the design considerations of casting with neat sketches. t10l
OR

Write short note on mechanical properties of materials' t6l
Q.1 (a)
(b) Explain in detail design considerations of machine parts' [10]

UNIT.II
joint' t8l
Q.2 (a) Write the design procedure of cotter

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[4E4143]

(b) It is required to design a square key for fixing a pulley on the shaft, that is 25mm
diameter. The shaft is transmitting 15 kW power at72O rpm. The key is made of
steel (Sn = 460 N/mm2) and the factor of safety is 3. For key material, the yield

strength in compression can be assumed to be equal to the yield strength in
tension. Determine the dimension of the key.
t8l
OR
Q.2 (a) What is knuckle joint? Where do you use knuckle joint? Give practical
examples.
t41
(b) The stresses induced at a critical point in a machine component made of steel
(Syt = 380 N 1mm2; are as follows
ll2)
o X = 100N/mm2
oy=40N/mm2
x xy = 80 N/mm2

Calculate the factor of safety by
(i) The maximum normal stress theory
(ii) The maximum shear stress theory
(iii) The distortion energy theory
UNIT-III
Q.3 (a) A semi - elliptic leaf spring used for automobile suspension consists of three
extra full - length leaves and 15 graduated - length leaves, including the master
leaf. The centre - to - centre distance between two eyes of the spring is lm. The
maximum force that can act on the spring is 75 kN. For each leaf, the ratio of
width to thickness is 9:1. The modulus of elasticity of the leaf material is 207000
N/mm2. The leaves are pre - stressed in such a way that when the force is
maximum, the stresses in all leaves are same and equal to 450 N/mm2. tl2l
Determine-
(i) The width and thickness of the leaves.
(ii) The initial nip
(iii) The initial pre - load required to close the gap 'c' between extra full -
length leaves and graduated length leaves.

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(b) What is the objective of shot peening of spring? t4l
OR

Q.3 (a) For a beam made of C.I- given below, determine the dimensions of the cross
section.

10kN

<-300mm+
Use followings:

Sut= 200 N/mm2

F.S. = 2.5

The depth of cross section is twice of the width.

Use maximum normal stress theorY. uzl
(b) What are the second type of lever and third type of lever? Give their
examples. t4l

e.4 It is required ro design a rigid.rrffiupling to connect two shafts. The input
shaft transmits 37.5 kW power at 180 rpm to the output shaft through the coupling.
Use following: 116l
Service factor = 1.5

Allowable shear stress for shaft = 76
#
N,
Allowable shear stress for keys & bolt = 39
mm'
N
Allowable cruishing stress for keys & bolt = 240 a
mm"
N;
Allowable shear stress for flanges = 16.67
.mm
Take Number of bolts = 4

l4E4t+3) Page 3 of4 [12680]

OR
Due to modification of
Q.4 (a) A solid shaft of diameter d is used in power transmission'
system, it is required to replace the solid shaft
by a hollow shaft of the
existing
same material and equally strong in torsion.
Further the weight of hollow shaft
Determine the outer diameter
per metre length should be half of the solid shaft'
t10l
of hallow shaft in terms of 'd''
t4l
(b) Explain equivalent twisting moment for shaft'
121
(c) What do you understand by torsional rigidity?

UNIT-V
strength'? t4l
Q.5 (a) What do you mean by 'Bolt of uniform
at A and
(b) A wall bracket is attached to a wall by means of four identical bolts' two
wall and prevented from
two at B. Assuming that the bracket is held against the
tensile stress in the bolts
tipping about C by all four bolts and using an allowable
on the basis of maximum principal
as 35 N/mm2. Determine the size of the bolts

stress theorY.
lr2)

25 kN

s00T
mml
-JL
i"% r- OR
I10l
Q.s (a) Give in detail, the design procedure of screw Jack'
t3l
(b) Explain self - locking of power screw'
t3l
(c) What do you mean by overhauling of power screw?

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