EXPERIMENT ON TORSIONAL VIBRATION OF A DOUBLE ROTOR SHAFT

AIM :: To study the torsional vibration of two rotor shaft system.

APPARATUS :: Vibration test rig , vernier caliper, two rotor shaft , scale, stopwatch…

THEORY ::  A rotor shaft system consists of a shaft with two rotors at both ends each, both rotor may rotate in the opposite direction [two rotors A&B having mass moment of inertia & the rotor A&B are converted at the end with shaft having stiffness ‘K’]

          

           

PROCEDURE :: 

·         Shaft is fixed at the two ends to the rotor with the help of chucks

·         One rotor is rotated at clockwise direction and another is rotated at anticlockwise direction .

·         The time for ‘n’ number of oscillation is determine with the help of stopwatch.

·         The time period and frequency and various other parameters are determined and the values are tabulated .

·         Experiment is repeated for different trials.

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QUESTIONS AND ANSWER OF TORSIONAL VIBRATION OF DOUBLE ROTOR SHAFT

·         Define  Resonance?

When frequency of the exciting force is equal to the natural frequency of the system it is called resonance . under such conditions the amplitude of vibration builds up dangerously .

·         Define degree of freedom ?

The degree of freedom of a vibrating body or system implies the number of independent coordinates which are required to define the motion of the body or s/m at given instant.

·         Simple harmonic motion

It is to and fro periodic motion of a particle in which

1.       Acceleration  is proportional to the displacement from the mean position.

2.       Acceleration  is always directed towards a fixed point which is the mean equilibrium position.

·         What are the causes of vibration in machines.

1.       Impact processes such as pile driving and blasting.

2.       Rotating or reciprocating machinery such as engine ,compressors and motors.

3.       Transportation vehicles such as trucks , trains and aircraft.

4.       Flow of fluid through pipes and without pipes.

5.       Natural calamities such as earthquakes.

·         Define natural frequency ?

It is frequency of vibration of a system which is undamped and without external excitation when it is disturbed.