Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 5th Sem 2151907 Design Of Machine Elements Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?V (NEW) EXAMINATION ? WINTER 2020
Subject Code:2151907 Date:20/01/2021
Subject Name:Design of Machine Elements
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Distinguish between open and cross belt drive.
03
(b) Solve the numbers of R5 basic series from 1 to 10.
04
(c) Decide appropriate manufacturing consideration in
07
design.
Q.2 (a) Explain stress concentration.
03
(b) Explain factors affecting endurance limit.
04
(c) A machine component is subjected to fluctuating stress
07
that varies from 40 to 100 N/mm2. The corrected
endurance limit stress for the machine components is
270 N/mm2. The ultimate tensile strength and yield
strength of the material are 600 and 450 N/mm2
respectively. Solve the factor of safety using (1) Gerber
theory (2) Soderberg line (3) Goodman line.
Q.3 (a) Design of thin cylinder.
03
(b) Classify types of springs.
04
(c) A semi elliptic multi leaf spring is used for the
07
suspension of the rear axle of a truck. It consists of two
extra full length and ten graduated length leaves
including the master leaf. The center to centre distance
between the spring is 1200 mm and width of leaves is 60
mm. The leaves are made of steel 55Si2Mo90 and
Syt=1500 N/mm2 and E=207 GPa and factor of safety is
2.5. The spring is to be designed for a maximum force
of 30 kN. The leaves are pre stressed so as to equalize
stress in all leaves. Solve (1) thickness of the leaves (2)
deflection at the end of the spring.
Q.4 (a) Design of thin spherical vessels.
03
(b) Analyze of stresses in helical spring.
04
(c) It is required to design a helical compression spring
07
subjected to a maximum force of 1.25 KN. The
deflection of the spring corresponding to the maximum
force should be approximately 30 mm. the spring index
can be taken as 6. The spring is made of patented and
cold drawn steel wire. The ultimate tensile strength and
modulus of rigidity of spring material are 1090 and
81370 N/mm2 respectively. The permissible shear stress
for the spring wire should be taken as 50 % of the
1
ultimate tensile strength. Design the spring and solve (1)
wire diameter (2) total number of coils.
Q.5 (a) Describe creep in belt.
03
(b) List advantages and disadvantage of chain drive.
04
(c) Design an equation for ratio of tensions on tight side to
07
slack side of flat belt drive.
Q.6 (a) List application of V belt drive.
03
(b) List advantages and disadvantage of belt dive.
04
(c) Design of pully for flat belt drive.
07
Q.7 (a) Define: (1) Pressure vessel (2) thick cylinder (3) thin
03
cylinder
(b) The inner diameter of a cylindrical tank for liquefied gas
04
is 250 mm. the gas pressure is limited to 15 MPa. The
tank is made of plain carbon steel 10C4 (Sut=340
N/mm2 and ?=0.27 ) and the factor of safety is 5.
Calculate the cylinder wall thickness.
(c) Explain principle stresses in thick cylinder.
07
Q.8 (a) Describe briefly Autofrettage.
03
(b) A seamless steel pipe of 100 mm internal diameter is
04
subjected to internal pressure of 12 MPa. It is made of
steel (Syt=230 N/mm2 and ?=0.27) and the factor of
safety is 2.5. Calculate the thickness of the pipe.
(c) Explain end closures with neat sketch.
07
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This post was last modified on 04 March 2021