JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II STRENGTH OF MATERIALS-II Previous Question Paper (December -2018 - R15)
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 and may have a, b, c as sub questions.
PART - A
Define the terms: i) Torsion ii) Torsional rigidity iii) Polar M.I.
Answer
i) Torsion is the state of a structural member subjected to twisting moments that tend to rotate it about its longitudinal axis. ii) Torsional rigidity is the product of the modulus of rigidity (G) and the polar moment of inertia (J), representing the resistance of a shaft to twisting per unit length. iii) Polar M.I. (J) is the second moment of area of a cross-section about the polar axis (the axis perpendicular to the plane of the cross-section passing through the centroid).
What do you mean by resilience of a spring?
Answer
Resilience of a spring is the total strain energy stored in the spring when it is deformed by an external load up to the elastic limit. It represents the capacity of the spring to absorb energy without undergoing permanent deformation.
A 3.0 m long column is hinged at one end and fixed at the other end. What is its equivalent length?
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What are the drawbacks of Euler’s theory of buckling?
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A column is of hollow section. Due to an eccentric load, maximum and minimum stresses are 7 and 1 N/mm2 (both compressive) respectively. If the eccentricity is doubled, what will be the maximum stress developed in column section?
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If principal M.I of a section are Iuu and Ivv, then what is the moment of inertia about an axis X-X inclined at angle θ to U-V axis?
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Define term Shear center. For a section symmetrical about one axis only, where the shear center is located?
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Determine the product of inertia of a rectangular section of width 4 cm and depth 6 cm about its centroidal axis.
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Give expressions for radial and hoop stress (Lame’s equation) in thick cylindrical shell subjected to internal pressure ‘p’.
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A thin cylindrical shell is made of steel with ʋ =0.3. It is subjected to an internal pressure ‘p’, what is the ratio of hoop strain to axial strain?
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PART - B
Obtain expressions for the twisting moment and bending moment components on an open-coiled helical spring subjected to axial load ‘W’?
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Find the size of a square shaft to transmit 75 kW at 120 rpm, if shear stress is not to exceed 50 N/mm2.
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A solid shaft has to transmit 112.5 kW at 250 rpm. Taking allowable shear stress as 70 N/mm2, find suitable diameter for the shaft, if the maximum torque transmitted at each revaluation exceeds the mean by 20%.
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Find the shortest length for a steel column with hinged ends having a cross-sectional area of 30 mm × 60 mm for which the elastic Euler’s formula is applicable. E = 200 GPa and assume proportional limit to be 250 Mpa.
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What is straight line formula for working stress under buckling, where it is used?
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What are the merits of Rankine’s load over Euler’s load in buckling?
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A column of a circular section, diameter ‘d’ and length L, buckles at a load of 25 kN, when the column is fixed at one end and free at the other end. If both the ends of the column are now fixed, what will be its buckling load?
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What is Core of a section? What is its importance?
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Determine the core for following sections: i) Rectangular section ii) Hollow circular section.
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A cast iron column of square section 400 mm × 400 mm is subjected to a compressive load of 500 kN acting at a point i.e, 60 mm away from X-X axis (ey) and 80 mm away from Y-Y centroidal axis (ex). Determine the resultant stresses at the extreme corners of the section.
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A simply supported beam of length 2.2 m carries a central load of 5 kN inclined at 30o to the vertical and passing through the centroid of the section. Determine: a) max. tensile stress b) max. compressive stress c) deflection due to the load d) Direction of neutral axis. Take E= 200×105 N/cm2.
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Determine the position of the shear center for a channel section of 120 mm × 120 mm (outside) and thickness 10 mm thick.
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Derive the expression for hoop and axial stresses developed in a thin cylindrical shell subjected to internal pressure ‘p’.
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A thin spherical shell of a diameter of 300 mm and wall thickness ‘t’ is subjected to internal pressure of 2.4 N/mm2. Determine the wall thickness ‘t’ if the hoop stress in the shell is limited to 60 Mpa. What is the change in diameter of the shell? Take E=105 kN/mm2 and ʋ =0.32.
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A pressure vessel of an internal diameter of 200 mm, an external diameter of 250 mm and a length of 1.0 m is tested under a hydraulic pressure of 20 Mpa. Determine the change in its internal and external diameters, if E = 208 kN/mm2 and ʋ = 0.3. If a strain gauge is mounted on the surface of the pressure vessel in an axial direction, what will be the strain reading?
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