F.Y. M.Tech. (Mechanical-Design Engineering) (Semester
Examination, 2018
(New CBCS)
advanced vibrations and acoustics
Day and Date Thursday, 6-12-2018 Total Marks 70
Time 10.00 a.m. to 1.00 p.m.
Instructions Solve any five questions.
Figures to the right indicate full marks.
Make suitable assumptions if necessary and state
them clearly.
1. Explain forced vibrations with constant harmonic excitation for a single
degree of system with damper. What are steady state vibrations and
transient vibrations 7
Find out the two natural frequencies and corresponding mode shapes for
a double pendulum with two point masses system with two masses m1 and
m2
suspended by strings of length I1 and I2. Take m1 m2 and I1 I2. 7
2. Derive an equation for the response of a damped system subjected to
an impulsive input 7
A three degree of freedom system is as shown below. Write the equations
of motions and represent these equations in matrix form. 7
3. Explain principle of dynamic vibration absorber. 7
Find the lower natural frequency of vibration for the system shown below
by Rayleigh's method.
Assume E 1.96 × 1011 N/m2 I 4 × 10-7 m4. 7
4. Determine two natural frequencies and corresponding mode shapes for
a two rotor torsional system. 7
Write a note on transverse vibrations of shafts continuous system). 7
5. Write a note on forced vibrations with nonlinear spring forces. 7
Explain power spectrum and power spectral density in case of
random vibrations 7
6. What are nonlinear vibrations Discuss in detail with examples. 7
Write a note on random vibrations. 7
7. Explain construction and working of FFT analyzer. 7
Write note on Sound intensity, dB scale and sound power. 7