Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 5th Semester (Fifth Semester) 2018-2019 RME 501 Machine Design 1 Question Paper
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B. TECH.
(SEM V) THEORY EXAMINATION 2018?19
? MACHINE DESIGN -I
T ime: 3 Hours Total Marks: 70
Note: 1. Attempt all Sections. If require any missing data; then choose suitably.
l.
2. Standard design data book is allowed.
SECTION A
Attempt all questions in brief. 2 x7= 14
What are the factors to be considered in the selection ot?materials for a machine element?
What are the methods of reducing stress concentration?
Compare the strength of a hollow shaft with that of a solid shaft of same diameter
and material of the diameter ratio of 0.5.
Write the numbers of active turns in terms of number of total numbers of turns for
different end connections of compression springs.
Why is the e?iciency of seltlloekjng square threaded screw less than 50%?
Describe the types of riveted joint. Also explain the various failure modes of rivets.
Under what circumstances ?exible couplings are used?
SECTION B
Attempt any three ofthe following: ? 7 x 3: 21
A shaft as shown in figure 1 is subjected to bending load of3kN,tw1sting moment of 1009 N- 111 "
and an axial pull of 15 RN F 1nd lhe notmal and shear stresses at point A and B . .
:2?qu
l
f" K?
1 51m 2
.. W 3.50 mm ?H
Figurc-l
A component machined from a plate made of steel 45C 8 (Sui: 630 MP3) is shown in
?gure 2. It s subjected to a completely reversed axial loading of 50 kN. The expected
reliabilit} is 90% and the factor ufsafety is 2, The size factor 15 0 85 Determine the plate
thickness t for infinite life. if the notch sensitivity factor is 0.8.
? (<1 : "rs? 5r
De?ne the ef?ciency of riveted joint? A steam boiler is to be designed for a working
pressure of 2.5 MPa with its inside diameter 1.6 m. Give the design calculations for the
longitudinal joints, The permissible stresses are 61 =75 MPa. Ts = 60 MPa and so = 125
MPa.
d.
. What do you understand bx preferred sizes? It
It is 1equ1red t0 de51gn a hel1ca1 compression Spring subjected to a max1n1um force of 1250 N. the
de?ection of the spring corresponding to the maximum force should be approx1mate1y 30 mm the
spnng index can be taken as 6 The spring is made of patented and cold drawn steel w11e The
ultimate tensile strength and modulus of rigidity of the spring mater1al are 1090 and 81370
N/mm2 respectively The permissible shear stress for the spring wire should taken as 50% of
ultimate tensile strength. Des1gn the spring and calculate:
a} Wire diameter
b) Mean coil diameter
c) Active number of coils
d) Total number of coils
c) Free length of the spring
1) Pitch of the CO1]
Design a protective type of cast 110n ?ange coupling for a steel sha? transmitting 15 kW
at 200 rpm and having an allowable shear stress of 40 MP3. The working stress 1n the
bolts should not exceed 30 MPa. Assume that the same material is used for the shaft and
key and that the crushing stress is twice the value of its shear stress. The maximum torque
is 259l'6greatc1 than the full load torque. The shear stress for cast iron is 14MPa?
SECTION C
Attempt any one part 01' the following:
~ 7 11 1:7 ._
1zi?quired to standardize load- -ca1ry1ng_
capacities of dampers in a manufacturing umt The mmimum and mimmum capae1t1cs
of such dumpers are 40 and 630kN The pany is interested in developing seven
models in this range Specify their 10adeam1n0 capacities. 2
. A mild steel shaft of 50 mm d1amet?cr ts subjected to a bending moment of 2030 N?m
and a torque T. If the yield p01111 Of?ie steel in tens1on is 200 MPa, fin
value of this torque without c111111ng \ ielding of the shaft according to 1, ' be maximum
principal stress: 2. The mammum shear stress; and 3. the maxirnum ?distortion strain
energy theory of weldmg?w 1 2,,
Attempt any one putt bf the following:
7x1=7
A cantilever beam made 01 cold drawn steel 20C8 (Sui ?540mem ) is subjected to a
completely reversed load of 1000 N as shown in below ?g 3 The corrected endurance limit
for the material 01 the beam may be taken as 123 8 V/mm2 I5etennine the diameter ?d? of
the beam for a 11fe of 10000 cy cles.
A bracket is riveted to a colutnntby 6 rivets of equal T
I 2.... "M1yg-m ....... .WV 4: ,2
m1 _?TW150WNW Pa: 21000 11-2
. mtmf...? .,..;...W..;...... www.22 Fig 3
22,215 1912:2511 ?
mesa" ?1
size as shown in following ?g.4. It carries a load of 75 mm?
60kN at a distance of 200 mm from the column 11? , 1} '
. . , . . . <23?
the maxunum shear stress 111 the rlvet 1s limited to ?mm g
150MPa, ?nd the diameter of the rivet. Ii
- " :11; #22212?, ,.? 21'1" 1.3?),3 ? ? '11"
5.
a.
Q
Attempt any one part of the following: 7 x 1=7
A transmission shaft supporting a spur gears B and a pulley D is shown in figure5. The
shaft is mounted on two bearings A and C, The diameter of pulley and the pitch circle
diameter of gear are 450 and 300 mm respectively. The pulley transmits 20 kW power at
500 rpm to the gear. P1 and P2 are belt tensions in tight and loose sides, while P1 and Pr
are tangential and radial components of gear tooth force. Assume, P1=3P2 and P.? ?
tan20?
The gear and pulley ate keyed to the shaft. The material of the shaft is steel 50C4 (Sm:
700 N/mm2 and SM = 460 N/mmz). The factors Kb and Kt of ASME code are 1.5 each.
Determine the shaft diameter using ASME code:
A mild steel sha? transmits 20 Wt 200 rpm It is subjected to a bending moment of
562. 5 N-m.Dete1mine the size 63? the sha? if the allowable shear stress 131212 MP3, and
the maximum tensile or compressive stress is not to exceed 58 MPa:2 What size of the
shaft will be required 1 ' ??ubjected to gradually applied load? ._ 2:
Attempt any one ?! of the following: ? 7 x 1=7
It 15 required to design square key for ?xing a gear to tra?smif a torque of l98943 68 N-
m The key is made of plain carbon steel having the yield point in tension and in
compression as 460 MPa and factor of safety 3 Detei?igne the dimensions of the key
. Design a spring for a balance to measure 0 to 1:000N over a scale of length 80 mm the
spring is to be enclosed in a case of 25 mm dAatneter The approximate number of turns is
30 The modulus of rigidity IS 85 GPa. AlSo?edlculale maximum shear stress induced.
Attempt any one part of the followmg: 7 x 1=7
Name the V?l'iOUS components ofjth Screw jack and their usual materials A single start
square threaded screw of men}; diameter 24 mm and pitch of 5mm is tightening by
screwing a nut whose mean diameter at bearing surface is 50 mm 1f the coef?cient of
friction between the nut and screw is 0. l and for the nut and bearing surface is 0.16 Find
the force required at the end of a spanner 0. 5-meter-long when the load on the screw is 10
kN.
Describe the various forms of the threads used for power screw, giving their merits and
demerits. Discuss the procedure for the design of the screw having squate threads.
This post was last modified on 29 January 2020