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Roll No.
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Total No. of Pages : 03
(Sem.-3)
Total No. of Questions : 09
B.Tech.(Automation & Robotics) (2011 & Onward)
STRENGTH OF MACHINE ELEMENTS
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Subject Code : BTAR-304
M.Code: 63004
Time: 3 Hrs.
Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
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- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.
SECTION-A
Q1. Answer briefly :
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- Define Lateral strain.
- Give the expression relationship between Young's modulus and Bulk modulus.
- Differentiate between a composite system and a composite bar.
- Define factor of safety and give its importance.
- Define principal planes.
- State assumption made in theory of simple bending.
- Define polar moment of inertia.
- Define helical springs.
- Enumerate the assumptions made in Euler's column theory.
- Define strut.
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SECTION-B
Q2. Determine the changes in length, breadth and thickness of a steel bar which is 4 m long, 30 mm wide and 20 mm thick and is subjected to an axial pull of 30 kN in the direction of its length. Take E = 2 × 105 N/mm² and Poisson's ratio = 0.3.
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Q3. A flat steel flat bar of 20 mm x 10 mm is fixed with aluminum flat of 20 mm × 10 mm so as to make a square section of 20 mm × 20 mm. The two bars are fastened together at their ends at a temperature of 26°C. Now the temperature of whole assembly is raised to 55°C. Find the stress in each bar. Take Es = 200GPa, Ea = 70 GPa. a? = 11.6 × 10-6/°C, aa = 23.2 × 10-6/°C.
Q4. An I section shown in figure below, is simply supported over a span of 12m. If the maximum permissible stress is 80 N/mm², what concentrated load can be carried out at a distance of 4 m from one support?
100mm11.5mm
7.5mm
N
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-A
225mm
11.5mm
FIG.1
Q5. Two shafts of same material and of same lengths are subjected to the same torque. If the first shaft is of a solid circular section and the second shaft is of hollow circular section, whose internal diameter is 2/3rd of the outside diameter and the maximum shear stress developed in each shaft is the same, compare the weights of the two shafts.
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Q6. Determine the Euler's crippling load for a T section of dimensions 10 cm × 10 cm × 2 cm and of length 5 cm, when it is used as strut with both ends hinged. Take Young's modulus for the joist as 2.0 × 105 N/mm².
Y10cm
2cm
X
X
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10 cm
y
2cm
Y
FIG.2
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SECTION-C
Q7 (a) A bolt is acted upon by an axial pull of 16 kN along with a transverse shear force of 10 kN. Determine the diameter of the bolt required according to different theories of failure. Elastic limit of the bolt material is 250 MPa and a factor of safety of 2.5 is to be taken along with Poisson's ratio of 0.3.
(b) At a point in a strained material, the principal stresses are 100 N/mm² (tensile) and 60 N/mm² (compressive). Determine the normal stress, shear stress and resultant stress on a plane inclined at 50° to the axis of major principal axis. Also determine the maximum shear stress at the point.
Q8. A simply supported beam AB of span 4 m carries a point load of 100 kN at its centre C. The value of I for the left half is 1 × 108 mm² and for the right half portion I is 2 × 108 mm². Find the slopes at the two supports and deflection under the load. Take E = 200 GN/mm².
A100 KN
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C
2m
RA = 50kN
FIG.3
2m
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RB = 50kN
B
Q9. The beam AC is simply supported at A and C and subject to the uniformly distributed load of 300 N/m plus the couple of magnitude 2700 N-m as shown in Figure. Write equations for shearing force and bending moment and make sketches of these equations.
Ay
X
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30N/m
RA
D
X
B
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C
3m
3m
RC
FIG.4
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2700N-m
3m
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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