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Course Code : AME1118/2009 R-2009 Reg. No :

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GAYATRI VIDYA PARISHAD COLLEGE OF ENGINEERING (AUTONOMOUS)Madhurawada, Visakhapatnam

Affiliated to JNT University K, KakinadaB.Tech. V-Semester Supplementary Examinations, November-2014

Dynamics of Machinery

(Mechanical Engineering)

Date : 20-11-2014 Time : 3 Hours Max. Marks : 60

1. Question No. 1 is Compulsory.

2. Answer any FOURfrom questions 2 to 8.3.

All parts of a Question must be answered in one place to get valued.

1. Answer the following in 4 or 5 sentences.

a) Define Gyroscopic couple.b) Differentiate between band and shoe brake.

c) What is meant by turning moment diagram or crank effort diagram?d) List and explain the effects of partial balancing of locomotives.

e) What is meant by isochronous governors?f) Define Logarithmic decrement.

g) Define Torsionally equivalent shaft.h) Difference between governor and flywheel.

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2. Period of oscillation of the pitching of a sea-vessel is 30 seconds. The angle transverses is 12o

the motion may be assumed to be simple harmonic. The mass of the rotor is 500 kg. Radius ofgyration of rotor is 40 cm. The speed of the rotor is 2000rpm.

a) Determine the magnitude of maximum gyroscopic couple cased by the rotors of the turbine.

b) find also the direction in which the bow will tend to turn when falling if the rotors are rotatingin clockwise direction as viewed from the aft.

c) What will be the maximum angular acceleration of the ship while pitching.

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3. Four masses A,B,C and D carried by a rotating shaft at radii 80mm, 100mm, 160mm and

120mm respectively are completely balanced. Masses B,C and D are 8kg, 4kg and 3kgrespectively. Determine the mass A and the relative angular positions of the four masses if the

planes are spaced 500mm apart.

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4. Each ball of a porter governor has a mass of 3kg and the mass of the sleeve is 15kg the governorhas equal arms each of 200mm length and pivoted on the axis of rotation. When the radius of

rotation of the balls is 120mm, the sleeve begins to raise up 160mm at the maximum speed.Determine:

(i) range of speed(ii) lift of the sleeve

(iii)

effort of the governor(iv)

power of the governor

What will be the effect of friction at the sleeve if it is equivalent to 8N.

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Course Code : AME1118/2009 R-2009 Reg. No :

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5. A machine of 100kg is supported on a spring of stiffness 700kN/m and has an unbalanced

rotating element, which results in a disturbing force of 350N and at a speed of 3000rpm.Assuming a damping factor of 0.20. Determine its amplitude of motion due to unbalance,

the transmissibility and the transmitted force.

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6. A single cylinder oil engine drives directly a centrifugal pump. The rotating mass of the engine,

flywheel and the pump with the shaft is equivalent to a 3 rotor system as shown in figure.

The mass moment of inertia of the rotors P,Q,R are 0.2, 0.4 and 0.1 kg-m2. Find frequency of

torsional vibration. The modulus of rigidity of the shaft material is 80GN/m2.

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7. What is the advantage of a self-expanding shoe brake? Derive the relation for the friction torquefor such a brake.

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8. The crank and the connecting rod of vertical single cylinder gas engine running at 1800rpm

are 60mm and 240mm respectively. The diameter of the piston is 80mm and the mass ofthe reciprocating parts is 1.2kg. At a point during the power stroke when the piston has

moved 20mm from the top dead centre position, the pressure on the piston is 800 kN/m2.

Determine the

(i) net force on the piston(ii) thrust in the connecting rod

(iii) thrust on the sides of cylinder walls(iv) engine speed at which the above values are zero

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