1
Seat No.: _____ Enrolment No.______
GUJARAT TECHNOLOGICAL UNIVERSITY
B.E. Sem-III Regular / Remedial Examination December 2010
Subject code: 131902
Subject Name: Machine Design & Industrial Drafting
Date: 15 /12 /2010 Time: 10.30 am – 01.30 pm
Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1
(a)
Differentiate between (with neat sketch): 04
1) crushing and compressive stresses
2) torsional and transverse shear stress
(b)
Define the following : 05
1) proof resilience 2) Preferred Number 3)Factor of Safety
4)Residual stress 5) principle stress
(c)
An offset link, fig. 1 has a clear swing of 10 mm. the radius of curvature of
curved part is more compare to swing of link. The cross section is shown, where
the thickness (t) of link is 26 mm. Find the load corresponding to a maximum
fiber stress of 100 N/mm
2
.
05
Q.2
(a)
Explain the important terminology of riveted joints and find the efficiency of the
double riveted lap joints with zig-zag riveting is to be designed for 13 mm thick
plates. Assume 80 MPa., 60 MPa and 120 MPa in tension, Shear and crushing
respectively. Also calculate pitch of rivets.
07
(b) 1. A circular shaft, d in diameter, is welded with annular fillet having throat
thickness of t. shaft is subjected to bending moment only. Determine the
moment of inertia of annular fillet weld.
03
2. Fig.2 shows 12 mm thick plates loaded by the forces of 100 KN applied
eccentrically. Determine the required lengths L
1
& L
2
of the fillet welds so
that they will be equally stressed in shear. Take working stress in shear for
side fillets to be equal to 80 N/mm
2
04
OR
(b)
A bracket is to be attached to a wall with the help of six rivets. The different
arrangements in which the bracket can be attached to the wall with these rivets
are shown in fig. 3. The maximum allowable stress in shear is 60 N/mm
2
.
Determine the way in which the rivets should be arranged so that the design is
economical. The bracket is required to support a load of 90 KN with an
eccentricity of 200 mm. also determine the diameter of rivet for the selected
arrangement.
07
Q.3
(a)
Define cotter, Why taper is provided in a cotter? And What is the purpose of
clearance in Cotter Joints?
04
(b)
Explain with neat sketch, design procedure of coupler. 04
(c)
It is required to design a cotter joint to connect two steel rods of equal diameter.
The permissible stresses for the rods, spigot end and socket end are σ
t
=96
N/mm
2
, σ
c
= 134 N/mm
2
& τ = 45 N/mm
2
. For cotter,
σ
t
=80 N/mm
2
, τ = 40 N/mm
2
. Each rod is subjected to an axial Tensile force of
60 KN. Calculate following dimensions:
1. diameter of spigot 2. width & thickness of cotter
3. thickness of socket collar
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