JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELEMENTS OF MECHANICAL ENGINEERING Previous Question Paper (April/May - 2018 - R16)
Part A is compulsory. Answer any one full question from each unit in Part B.
PART - A
Answer all questions:
Explain Ductility, malleability and brittleness.
Answer
- Ductility: The ability of a material to undergo significant plastic deformation under tensile stress before rupture, allowing it to be drawn into wires.
- Malleability: The property of a material to be deformed under compressive stress, allowing it to be hammered or rolled into thin sheets without cracking.
- Brittleness: The tendency of a material to fracture or fail with little to no plastic deformation when subjected to stress, typically occurring suddenly.
What is the importance of modulus of rigidity and bulk modulus?
Answer
- Modulus of Rigidity (G): Defines the material's resistance to shear deformation. It is critical for calculating the deflection of shafts under torsion and determining the stiffness of structural members subject to shear loads.
- Bulk Modulus (K): Measures a material's resistance to uniform compression. It is essential in fluid mechanics and high-pressure engineering to predict volume changes under hydrostatic pressure.
Sketch the S.F diagram for a cantilever with UDL and point load at the end.
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What assumptions are made in the derivation of bending moment formula?
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How to distinguish between longitudinal and hoop stress?
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How to find change in volume of spherical shell?
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What is the principle of working of C.I engine?
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How the friction Horse power is calculated?
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What is the effect of centrifugal tension in the belt?
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Sketch the working of epi-cyclic gear train.
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PART - B
What is the relation between E and N?
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A steel hoisting wire of 5 mm. diameter and 100 m. long is used vertically to lift a weight of 2000 N. at its lower end. Find the total elongation of wire. The specific weight of steel is 78.5 KN/m3, E = 205 KN/mm2.
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Draw stress strain curve for a mild steel specimen subjected to tension and explain about the importance of various salient points.
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The following data is related to a bar subjected to tensile test: Diameter of bar = 30 mm. Tensile load = 50 KN. Gauge length = 300 mm. Extension of bar = 0.110 mm. change in diameter = 0.004 mm. Calculate poisson’s ratio and values of three modulie.
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Draw shear force and bending moment diagram for a simply supported beam of span of 6 m. one point load of 2 kN is placed 1 m away from left support and 4 kN is placed 1 m away from right support. A UDL of 2 kN/m is placed in the centre portion of beam over a length of 2 m. Find the maximum BM and its position.
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A cantilever of 2 m length carries uniformly varying load of 15 kN/m at free end to 50 kN/m at the fixed end. Draw S.F and B.M diagrams.
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Derive equation to find the thickness of shell of cylindrical drum subjected to internal pressure of ‘p’.
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A thin spherical shell of 1.5 m inner diameter and 3 mm. thick is filled with water under a pressure of 15 bar. Find the stress developed in the shell. Take young’s modulus as 200 Gpa and poisson’s ratio 0.3.
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Calculate the increase in volume of a boiler shell of 1 m. diameter 3 m. length, when it is subjected to an internal pressure of 2N/mm2. Find the wall thickness such that the tensile stress in the shell is 20 N/mm2 due to pressure. Take E = 200 GPa. And poisson’s ratio = 0.3.
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Sketch and explain the construction and working of two stroke petrol engine.
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Distinguish between two stroke and four stroke engines.
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How to find specific fuel consumption and friction power?
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In a diesel engine cylinder diameter is 20 cm. stroke 30 cms. speed 600 rpm. Brake load is 70 kg on a drum diameter of 2 m. oil consumption is 200 gms per min. calorific value of fuel is 10,000 Kcal/kg. Find BHP and break thermal efficiency.
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Derive an equation to find length of open belt drive.
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Differentiate between belt and rope drive.
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How the gears are classified and mention their applications?
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Derive an equation to find the ratio between the tension of belt drive.
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