Mechanical

1. 1
Machinery Fault Diagnosis and Signal Processing
FREE AND FORCED RESPONSE
Prof. A. R. Mohanty
MECHANICAL ENGINEERING DEPARTMENT

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Base excitation
Spring
(k)
Mass (m)
Damper
(c)
Base

3. 3
Demonstration of base excitation (vibrating support)
1000 N/m
1000 N/m
1000 N/m
1000 N/m
Mass = 0.785 kg

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Demonstration of base excitation (vibrating support)

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Demonstration of base excitation (vibrating support)

6. 6
Numerical example (vehicle on wavy road)*
4×104 N/m
1000 kg
2000 Ns/m
displacement
5 m
0.02 m

7. 7
Numerical example (vehicle on wavy road)

8. 8
Tuned Mass Damper (TMD)
K1
M1
K2
M2
F0 sin(ωt)

9. 9
Demonstration of TMD
1 kg
0.1 kg
1000 N/m
100 N/m
Forc
e

10. 10
Body without mass damper
Maximum displacement = 0.054 m
Body with mass damper
Maximum displacement = 2.69e-6 m
Demonstration of TMD

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Tuned Mass Damper (TMD)
Figure: Stockbridge damper
• A tuned mass damper is a device that is attached to a structure in order to reduce its
response.
• The frequency of TMD is tuned to a particular structural frequency.
• Tuned mass dampers are widely used in transmission line, automobiles, and
buildings.

12. Moose Damper
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13. Resources
• A. R. Mohanty, “Machinery Condition Monitoring-Principles
and Practices” CRC Press, 2014.
• www.iitnoise.com
• Contact Prof. A. R. Mohanty at 94340-16966 or email:
amohanty@mech.iitkgp.ernet.in
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14. Thank you!
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