Bangalore University 2006-2nd Sem Diploma Mechanical Engineering I - Strength of material Supplementary Stdte - Question Paper
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Third Semester Diploma ( Supplementary ) Examination, 2006
CIVIL BOARD
STRENGTH OF MATERIALS ( Course Codes : AT, ME, MP, MY)
Time : 3 Hours ] [ Max. Marks : 100
Instructions : 1) Section I is compulsory.
ii) Answer any two full questions each from Sections II and HI & any one full question each from Sections IV &V. ' r
5x1 = 5
1.
itiiply supported beam for any loading the B.M. at supports will
SECTION -1
with appropriate word/words :
iflT Poisson ratio is always............... unity.
/
iii) The polar modulus of a hollow shaft is
iv) The M.I. of circular section about its centroidal axis is................
-
-Vr.. >'
V) If p i and p 2 are principal stresses jfchen maximum shear stress will be ................
b) Define the following : 5x1 = 5
Bulk modulus
ii) Moment of Inertia
iii) Thick cylinder
iv) Point of contraflexure
v) Moment of resistance.
SECTION - n
2. a) A cast iron column has an internal dia. of 200 mm. What should be the minimum external dia. so that it may carry a load of 1-6 MN without
exceeding stress of 90 N /mm 2 ? 5
b) A mild steel bar of 25 mm dia. 200 m length has an extension of 0-15 mm under a load of 75 kN. Loaded elastic limit is 130 kN and the maximum
load is 250 kN. The total extension is 55 mm. Dia. at the fracture is 18-5 mm.
Find :
i) Young's modulus . C?
ii) Maximum stress
iii) Percentage elongation
iv) Percentage reduction in area. 10
3. a) A steel bar 250 mm long, 50 mm x 50 mm in cross-section is subjected to a
pull of 300 kN. Calculate the change in volume if 1/m = 0-25.
Take E = 2 x 10 5 N/rmn2 9
b) Two parallel walls 10 m apart are stayed together by a steel rod of 50 mm dia. through metal plates & nuts at both ends. The nuts are tightened,
. when the rod is at a temperature of 150*C. Determine the stress in,$ie rod when the temperature falls down to 5i0*C, if
i) the ends do not yield,
ii) the ends yield by an amount 10 mm. *' \
Take E = 200 kN / mm 2
a = 0 0000125/C. . *<&&& .6
4. a) A bar of 20 mm dia. is subjected to a pull of -mcared-
extension on a gauge length of 200 mm is 0*12 mm artmmhainge in "dia. is 0-0036 mm. "
> Calculate ;' "
i) Young's modulus
ii) Poisson's ratio rfr
iii) Rigidity Modulus ,
iv) Bulk modulus. 9
b) At a point in a strained material the principal stresses acting are
100 N/mm 2 & 60 N/mm 2 both tensile.
Find :
i) Normal stress
ii) Tangential stress
iii) Resultant stress,
of the plane is inclined at 60* to major axis. 6
SECTION-m
5. a) Draw the S.F.D and B.M.D. for a cantilever beam of 6 m long which carries
a point load of 2 kN at the free end and a u.d.l. of 3 kN/m for a length of
2 m from the fixed end. 6
b) A simply supported beam of 8 m carries a u.d.L of 5 kN/m for a length of 3
m from the left support and point loads of 6 kN, 5 kN & 4 kN at 4 m, 5 rn and 6 m from the left support. Draw SFD & BMD. 9
Locate the centroid of an angle section ISA 100 mm x 80 mm x 10 mm with its longer leg vertical. 6
The top flange of an I-section is 60 mm x 20 mm, web 100 mm x 20 mm and the bottom flange is 100 mm x 20 mm. Find Moment of Inertia about its centroidal XX and YY axes. 9
a]
b)
a)
b)
A timber beam of rectangular cross-section is simply supported over a span of 6 m carrying a tucLl of 2 kN/m over entire span. Calculate the v.ldth and depth of beam if the stress is not to exceed 8 N/mm 2.
Take ratio of depth to width as 2. 6
Select a suitable dia. of solid shaft of circular section to transmit 112*5 kN of power at 200 R.P.M., if the allowable shear stress is 75 N/inm 2 and the allowable twist is 1* in a length of 3 m.
Take C = 0-8 x 10 5 N/mm 2. S
SECTION - IV
Design a double riveted double cover butt joint to connect two plates 10 mm thick with 20 mm dia. rivets. T&ke/j s*90 N|/fnin f 80N/mm
a)
b)
2, f b= 180 N/mm2. - ; ; v v 9
A welded joint is provided two tie bars 150 mm x 100 mm as shown in fig. I. Hie working stress in the tie bar is 120 N/mm 2< Investigate the design, if the size of fillet weld is 12 mm. Take the working stress in the end fillet as 100 N/inm 2 and for diagonal fillet as 70 N/mm 2. 9
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ALL DIMENSICXS AKE IN mm iMrf ri' |
The dia. of riveted boiler is 2-5 m and is designed to withstand a pressure of 1 N/mm 2. If the longitudinal efficiency is 70% and the efficiency of circumferential joint is 40%, determine the thickness of plates required. Take the stress in the plate as 150 N/mm 2. 9
A thick cylindrical cell of 160 mm internal dia. is 45 mm thick. The cell is subjected to an internal pressure of 52-5 N/mm 2. Find the maximum and minimum intensities of loop stress across the section. 9
9. a)
b)
SECTION-V
10. A beam of 10 m span simply supported at its ends, carries concentrated loads of 30 kN, 50 kN and 20 kN acting at 2 m, 5 m and 7 m from the left support respectively. Determine the reactions of supports graphically. 12
11. Five forces act an a rigid bar as shown in Jig. 2. Find the value & position of resultant of these forces graphically. 12
S
ALL DIMENSIONS ARE IN mm Fig. (2)
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| Earning: Approval pending. |
