RTU 2016 Question Paper Semester VI Mechanical Engineering Vibration Engineering

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Instructions to Candidate
Min. passing *#?ilI:tYffi ;:
s:_

Attempt any
five questions, serectrng one
question
equar marks sc!te.notic-";;;;;*, from each unit. Art
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data you feel mrrrng-ffi
and stared rr"orrll.'' suitabry be assumed
uruts of quantifies
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must be stuted crearry.

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a e a e i e u e n i

UNIT-I
Q.l (a) Discuss various methods
used in controlling
(b) Exptain term loudness. industrial noise.
How does it vary with t8l
the frequency?
is taken in account How this variation
in the subjective assessment.

Q.l (a) What are the auditory
q t8l
and non _ auditory
(b) Derive an equadon effects of noise.
for finding out sound t8l
intensity
---J at
qL a distance
of sound of known r from the source
sound power level"
t8l
[687014]
Page 1 of4
[174201

UNIT.II
Q'2 (a) A 5 kg mass attached to the lower end of a spring, where upper end fixed,
vibrates with a natural period of 0.45 sec. Determine
the natural period when a
2'5 kg mass is attached to the midpoint of the same
spring with upper and lower
ends fixed.
tgl
(b) A shaft supported freely at the ends has a mass of 100 kg placed 25
cmfrom one
end' Find the ffequency of the natural transverse vibration
if the length of the
shaft is J5 cm,E = 200 GN/M2 and shaft diameter
is 4 cm. t8l
OR
Q'2 (a) what do you understand by under - damped system, over damped system and
critically - damped system and its use? Explain.
[3+3+4=10]
(b) A vibratory system in a vehicle is to be designed with the following parameters:
K = 100N/m, c = 2N- Sec/m, m = 1 kg

calculate the decrease of amplitude from its starting value
after complete
oscillations and (b) the frequency of oscillation.
I6l

UNIT.III
Q.3 (a) Derive an expression for amplitude and phase angle of vibrations because of a
rotating unbalance.
t8l
(b) A vibrating system having mass 1 kg is suspended by a spring
stiffness 1000N/m
and it is put to harmonic excitation of l0 N. Assuming
viscous damping,
determine.
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(i) The resonant frequency
(ii) The phase angle at resonance
(iii) The amplitude at resonance
(iv) The frequency corresponding to the peak amplitude and Take
C=40N-Sec/m.

[68701.4] Page 2 of 4
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OR
Q'3 (a) An electric motor is supported on a spring and
a dashpot. The spring has the
stiffness 6400 N/m and the dashpot
offers resistance of 500 N at 4.0
m/sec. The
unbalanced mass 0'5 kg rotates
at 5 cm radius and the total mass
of vibratory
system is 20 kg. The motor runs at
400 rpm. Determine:
(i) Damping factor
(ii) Amplitude of vibration and phase angle
(iii) Resonant speed and resonant amplitude
and
(iv) Forces exerted by the spring and dashpot
on the motor. r2+3+3+2=r0l
(b) A spring mass damper system is subjected
to a harmonic force. The amplitude
is
found to be 20 mm at resonance and
10 mm at a frequ ency 0.74 times
the
resonant frequency. Find the damping
ratio of system.
t6l
NIT.IV
Q'4 (a) Explain the principle of undamped dynamic vibration
absorber. tgl
(b) Figure shows a vibrating system having
two degree of freedom. Determine the
tow the two natural frequencies of vibrations
and the ratio of amplitudes of the
motion of m1 and m2 for the two mode
of vibration.
t8l

[6E701.4] Page 3 of4
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OR
Q.4 (a) Explain principle & working of centrifugal pendulum absorber.
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(b) A machine runs at 5000 rpm. Its forcing frequency is very near to its natural
frequency. If the nearest frequency of the machine is to at least 20To from the
forced frequency, design a suitable vibration absorbed for the system. Assume
the mass of the machine as 30 kg.
t8t
UNIT-V
Q.s (a) Write short note on Stodola's Method.
t8l
(b) using matrix method, Determine the natural frequencies of the system shown in
figure.
t8l

OR
Q.5 Derive governing equation for the torsional vibration of a shaft fixed at both end. Find
the frequency equation and mode shapes for the same.
t16l

16870141 Page 4 of 4
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