JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II STRENGTH OF MATERIALS - II Previous Question Paper (December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
Define the stiffness of a spring and write down an expression for the same of a open coiled helical spring.
Answer
Stiffness (k) is defined as the load required per unit deflection of the spring. For an open coiled helical spring, the stiffness is given by:
where G is the shear modulus, d is the wire diameter, D is the mean coil diameter, n is the number of turns, α is the pitch angle, and ν is Poisson's ratio.
Derive an expression for the power transmitted by a shaft.
Answer
The power transmitted by a shaft is the product of the torque (T) and the angular velocity (ω). Given torque T in N-m and rotational speed N in rpm, the angular velocity is ω = (2 π N) / 60. Therefore, the power (P) in Watts is:
Distinguish between the modes of failure of short and long columns.
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What are the assumptions made in the derivation of Euler’s critical load?
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What are the conditions for stability of a concrete retaining wall?
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Obtain the core of a circular section of radius ‘R’.
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Differentiate between thin cylinders and thick cylinders.
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A spherical shell of diameter 500 mm is subjected to an internal fluid pressure of 5 N/mm2. Find the required thickness of the shell if the permissible stress is limited to 62.5 N/mm2.
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Define unsymmetrical bending.
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What is shear center of a section and indicate the shear centre of a channel section.
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Part B
A solid circular shaft is required to resist bending moment of 90 kNm and twisting moment of 25 kNm. If the yield stress of the shaft material is 250 N/mm2, design the shaft according to (a) maximum strain energy theory of failure and (b) maximum principal stress theory of failure.
Answer
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An open coiled steel helical spring with 10 coils is made up of a steel wire of 12 mm, the mean diameter of helix is 125 mm and the angle of helix is 15°. Determine the maximum axial load that can be applied on the spring if the maximum bending stress and the maximum shear stresses are limited to 125 N/mm2 and 65 N/mm2 respectively. Also determine the stiffness of the spring.
Answer
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Design a hollow circular steel strut of length 5 m, both ends fixed, is subjected to an axial load of 600 kN. Assume the ratio of internal diameter to the external diameter is 0.8 and factor of safety is 2. Use Rankine’s formula. The Rankine’s constants are 320 MPa and 1/7500.
Answer
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A 3 m long steel hinged-hinged tubular strut with external and internal diameters of 125 mm and 100 mm, respectively, is subjected to an axial load of 25 kN and a transverse load 50 kN at its mid-span. Determine the maximum bending moment.
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A concrete dam 12 m high, 4 m wide at the top and 8 m wide at the base has its water-face vertical and retains water to a depth of 10 m. Find the maximum and minimum stress intensities at the base. Assume the unit weight of concrete is 24 kN/m3.
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A curved beam semi-circular in plan has 4 m radius and supported on three equally spaced supports. The beam carries uniformly distributed load of 25 kN/m of the curved length. Draw the shear force and bending moment diagrams.
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Find the change in the diameter, change in length and change in volume of a steel cylindrical shell of thickness 10 mm, 250 mm diameter and 4 m long carrying a fluid at a pressure of 5 N/mm2.
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A steel compound cylinder is made by shrinking a cylinder of external diameter 300 mm and internal diameter 200 mm over another cylinder of external diameter 200 mm and internal diameter 150 mm. The radial pressure at the junction after shrinkage is 10 N/mm2. Find the final stresses if the cylinder is subjected to an internal fluid pressure of 60 N/mm2.
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A cantilever beam of span 1.8 m has an unequal angle section, 100 mm×75mm × 10 mm, with the longer leg vertically downward. It carries a concentrated load of 25 kN at a distance of 1.5 m from the support and in a plane making 30° with respect to vertical. Determine the maximum stress at the support section.
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A simply supported beam of span 3.6 m has an unequal angle section, 125mm×75mm×10mm, is placed with the long leg vertically downward. Determine the central concentrated load that can be placed on the beam in order the maximum stress due to bending is not to exceed 150 N/mm2? Also determine the maximum deflection.
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