Janardan Rai Nagar Rajasthan Vidyapeeth 2006 B.Tech Aeronautical Engineering THEORY OF VIBRATION - I - Question Paper

Model Question Paper

B.TECH AERONAUTICAL ENGINEERING

BTAE4 THEORY OF VIBRATION - I

Time : 3 Hrs Maximum Marks : 75

Instructions :

1.Question paper is divided into group A,B and C.

2.Each group is of 25 marks.

3.Figure to the right in bracket indicate marks.

4.Handwriting should be neat and eligible.

GROUP A (25 Marks)

Answer any three questions (Question 1 is compulsory)

1)      Derive expression for work done by a vibrating system (5)

2)      Derive expression for series and parallel connected springs in a vibrating system with n number of springs with one mass m (10)

3)      a) What is critical damping? (10)

b) Derive expression for critical damping and its co efficient of damping for a vibrating system

4) Explain vibration isolation and transmissibility with reference to installation of machines to the ground. (10)

5) Briefly explain the following a) LVDT, b) untuned viscous damper (10)

GROUP B ( 25 Marks)

Answer any three questions (Question 6 is compulsory)

1)      Write short notes on frahams reed tachometer (10)

2)      A gun barrel of mass 600 kg has a recoil spring of stiffness 294 KN/m if the barrel recoils 1.3m on firing determine the following

a)      The initial recoil velocity of the barrel.

b)      The critical damping coefficient of the dashpot, which is engaged at the end of the recoil stroke

c)      The time required for the barrel to return to a position 5 cms from the initial position (10)

3)      Derive an expression using differential equations for a two degree of freedom system (10)

4)      Represent harmonic vibration in complex method (10)

5)      Classify different vibrations in detail with graphical representation (10)

GROUP C (25 Marks)

11 (A) Fill in the blanks (Each question carries 2 Marks ): (10)

1)      Number of cycles per unit time is

a)      resonance b) cycle time c) frequency d) none of these

2)      Piston, cylinder, dashpot are parts of which of the following damping

a)      eddy current b) viscous c) coulombs d) slip

3)      Earth quake occurs with

a)      free vibration ) forced vibration c) random vibration d) none of these

4)      The system which follows logarithmic decrement

a)      over damped b) under damped c) critical damped d) all of these

5)      When a shaft is twisted by an angle of q the type of vibration is

a)      free b) forced c) natural d) torsional

(B) Choose the best answer (Each question carries 2 Marks ): (10)

1)      When the frequency of external excitation is equal to the natural frequency of the system the frequency is called as ---------

2)      Resistance to motion of a vibrating body is ------------

3)      The type of vibration experienced by shaft carrying rotors rotating -------------

4)      When a rotor is rotating with a speed to create resonance is -----

5)      A vibratory system has damping C > Cc critical damping is --------------

( c ) State true or false (Each question carry 1 Mark ): (5 )

1)      Vibration induced by external force is called free vibration.

2)      A vibrating system has damping C< Cc critical damping is under damped system.

3)      Air compressor, IC Engines is examples of forced vibration systems.

4)      A vibration absorber can undo vibrations completely.

5) All the vibration measuring instruments can be called as seismic instructions.