Engineering Dynamics Lab Report: Vibration Isolation Laboratory

Vibration Isolation Laboratory
Engineering Dynamics




2nd Year
BEng Mechanical Engineering
Engineering Dynamics E2

,ABSTRACT
An experimental setup that consisted of vibrating mass as a result of variable vibration from
a moving base has been used to study the principles of vibration isolation. There have been
few differences between theoretical and experimental results, especially at low stimulating
frequencies where it is expected that system instability and human error (inaccuracy) in
measuring equipment will be more prevalent.
The investigation demonstrated that this device experiences vibration isolation between
roughly 30-100Hz. The transmissibility is positive between 5 and 30 Hz (amplify range), and
when the exciting frequency approaches the system's natural frequency at around 18 Hz, the
amplitude ratio increases until it reaches maximum (resonance). Secondary resonance
develops over 100 Hz due to the system's non-linear characteristics, which are a result of the
interaction between the system's non-linear stiffness, damping, and friction.




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, Contents
Abstract ................................................................................................................................................... 2
1.0 INTRODUCTION ........................................................................................................................... 4
2.0 THEORY ....................................................................................................................................... 5
2.1 System Modelling.................................................................................................................... 5
2.2 Asymptotes ............................................................................................................................. 5
2.3 Log-Log Plotting ...................................................................................................................... 6
2.4 Comparing experimental and theoretical results ................................................................... 6
3.0 APPARATUS USED IN THE LABORATORY..................................................................................... 7
3.1 Digital Oscilloscope ................................................................................................................. 7
3.2 Digital Multimeter ................................................................................................................... 7
3.3 Vibration Mass Spring Damper ............................................................................................... 7
4.0 METHODOLOGY .......................................................................................................................... 8
5.0 RESULTS AND DISCUSSION.......................................................................................................... 9
5.1 Theoretical Data Calculations ................................................................................................. 9
6.0 CONCLUSION ............................................................................................................................. 13
8.0 BIBLIOGRAPHY .......................................................................................................................... 14
APPENDIX A – FIGURES ......................................................................................................................... 15




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