Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 5th Sem 2152508 Design Of Machine Elements Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?V (NEW) EXAMINATION ? WINTER 2020
Subject Code: 2152508 Date: 03/02/2021
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.
4. Use of PSG design data book permitted.
MARKS
Q.1 (a) Explain completely reversed or cyclic stresses.
03
(b) Discuss Gerber method for combination of stresses.
04
(c) Determine the thickness of a 120 mm wide uniform plate for safe
07
continuous operation if the plate is to be subjected to a tensile load that
has a maximum value of 250 kN and a minimum value of 100 kN. The
properties of the plate material are as follows: Endurance limit stress =
225 MPa, and Yield point stress = 300 MPa. The factor of safety based
on yield point may be taken as 1.5.
Q.2 (a) Give characteristics of material for friction surfaces.
03
(b) Explain positive clutch and friction clutch.
04
(c) Discuss design procedure of simple band brake.
07
Q.3 (a) Draw stress distribution diagram of thick cylinder subjected to an
03
internal pressure.
(b) Give classification of pressure vessels.
04
(c) A cast iron cylinder of internal diameter 200 mm and thickness 50 mm
07
is subjected to a pressure of 5 N/mm2. Calculate the tangential and radial
stresses at the inner, middle (radius = 125 mm) and outer surfaces.
Q.4 (a) Give classification of bevel gear.
03
(b) Explain any four terms of worm gear.
04
(c) Discuss step by step design procedure of C- clamp.
07
Q.5 (a) Explain coefficient of fluctuation of speed.
03
(b) Prove that fluctuation of energy in flywheel E = m R2 2Cs.
04
(c) The intercepted areas between the output torque curve and the mean
07
resistance line of a turning moment diagram for a multicylinder engine,
taken in order from one end are as follows:
? 35, + 410, ? 285, + 325, ? 335, + 260, ? 365, + 285, ? 260 mm2.
The diagram has been drawn to a scale of 1 mm = 70 N-m and 1 mm =
4.5?. The engine speed is 900 r.p.m. and the fluctuation in speed is not
to exceed 2% of the mean speed. Find the mass and cross-section of the
flywheel rim having 650 mm mean diameter. The density of the
material of the flywheel may be taken as 7200 kg / m3. The rim is
rectangular with the width 2 times the thickness.
Q.6 (a) Explain terms used in helical gears.
03
(b) Give advantages and disadvantages of gear drive.
04
(c) A bronze spur pinion rotating at 600 r.p.m. drives a cast iron spur gear
07
at a transmission ratio of 4 : 1. The allowable static stresses for the
1
bronze pinion and cast iron gear are 84 MPa and 105 MPa respectively.
The pinion has 16 standard 20? full depth in volutes teeth of module 8
mm. The face width of both the gears is 90 mm. Find the power that
can be transmitted from the standpoint of strength.
Q.7 (a) Explain conical and volute springs.
03
(b) Discuss surge in springs.
04
(c) A helical spring is made from a wire of 6 mm diameter and has outside
07
diameter of 75 mm. If the permissible shear stress is 350 MPa and
modulus of rigidity 84 kN/mm2, find the axial load which the spring
can carry and the deflection per active turn.
Q.8 (a) Derive equations for maximum efficiency of a square threaded screw.
03
(b) Explain types of screw threads used for power screws.
04
(c) Discuss complete design procedure of Screw jack.
07
*************
2
This post was last modified on 04 March 2021