vibration isolation and it's objectives

1. PRESENTATION
ON
“VIBRATION ISOLATION
AND
BASE EXCITATION”
DYNAMICS OF MACHINERY
SUBMITTED BY:
HIMANSHI GUPTA (140120119057)/ ME/A2
GUIDED BY:
PROF. SAMEER RAVAL
(2161901)
GA N D H IN A GA R IN STITU TE OF
TEC H N OLOGY

2. INTRODUCTION
• Vibrations are produced in machines having
unbalanced masses or forces
• High vibration levels can cause machinery
failure, as well as objectionable noise levels
• A common source of objectionable noise in
buildings is the vibration of machines that are
mounted on floors or walls

3. SOURCES OF
VIBRATION
EXAMPLES
Rotating and reciprocating Unbalance Pumps, Turbines, Electric Generators,
Compressors
Misalignment and wear of tools Manufacturing – machining
Seismic Vibrations Buildings, Bridges, Chimneys and
Cooling Towers
Wind (Pressure loading) Tall Structures
Small magnitude vibrations E.g.
Pedestal and vehicular traffic
Sensitive systems like optical
instruments, microscopes,
Nanofabrication
Impact and shock loads Hammer and presses, in vehicles due
to bumpy/ irregular nature of road

4. VIBRATION ISOLATION
• Vibration isolation is the process of isolating
an object, such as a piece of equipment, from
the source of vibration
• The effectiveness of isolation is expressed in
terms of force or motion
• Lesser the amount of force or motion
transmitted to the foundation greater is said to
be the isolation

8. TYPES
PASSIVE VIBRATION ISOLATION
• Refers to vibration isolation or mitigation of
vibrations by passive techniques such as rubber
pads or mechanical springs
 ACTIVE VIBRATION ISOLATION
• Also known as electronic force cancellation
• Employs electric power, sensors, actuators, and
control systems for vibration isolation

9. OBJECTIVES
The basic objectives of vibration isolation are:
• To protect the delicate machine from excessive
vibration transmitted to it from its supporting
structure
• To prevent vibratory forces generated by
machine from being transmitted to its
supporting structure

10. MECHANISM OF
VIBRATIONS TRANSMISSION
SOURCE
PATH
RECEIVER

11. VIBRATION ISOLATORS
• The vibration isolation may be obtained by
placing materials, called vibration isolators in
between the vibrating body and the supporting
foundation or structure

12. PASSIVE VIBRATION ISOLATORS
METALLIC
SPRING ISOLATION
PAD
ISOLATION HANGER PNEUMATIC ISOLATOR

13. ACTIVE VIBRATION ISOLATORS
FRAME MOUNTABLE
ACTIVE HARD-MOUNT
PIEZOELECTRIC
VIBRATION CONTROL
SYSTEM
ACTIVE VIBRATION
ISOLATION TABLE

14. IMPORTANT CONSIDERATIONS WITH
VIBRATION ISOLATOR SELECTION
1) Machine Location :
• As far away from sensitive areas as possible
• And on as rigid a foundation as possible
2) Proper sizing of isolator units :
• Correct stiffness
• Sufficient travel to prevent bottoming out during shock
loads, or during system startup and shutdown
3) Location of isolators :
• Isolators should be equally loaded, and the machine
should be level

15. 4) Stability :
• Sideways motion should be restrained with snubbers
• The diameter of the spring should also be greater than its compressed
height
5) Adjustment :
• Springs should have free travel, should not be fully compressed, nor
hitting a mechanical stop
6) Eliminate vibration short circuits :
• Any mechanical connection between machine and foundation which
bypasses the isolators, such as pipes, conduits, binding springs, poorly
adjusted snubbers or mechanical stops
7) Safe operation :
• To avoid a spring break, you must have mechanical supports on which
the machine can rest without tipping

16. VIBRATION ISOLATION
MATERIALS
• The materials normally used for vibration
isolation are rubber, felt, cork, metallic
springs, etc.
• These are put between the foundation and the
vibrating body

17. RUBBER FELT
CORK METALLIC
SPRING

18. BASE EXCITATION
• It models the behavior of a vibration isolation
system
• The base of the spring is given a prescribed
motion, causing the mass to vibrate
• This system can be used to model a vehicle
suspension system, or the earthquake response
of a structure

19. FBD OF SDOF BASE
EXCITATION SYSTEM
…(1)

20. • For a car,
• The steady-state solution is just the superposition
of the two individual particular solutions
(system is linear)
(1)

21. PARTICULAR SOLUTION (SINE TERM)
• With a sine for the forcing function,

22. PARTICULAR SOLUTION (COS TERM)
• With a cosine for the forcing function, we showed

23. MAGNITUDE X/Y
• Now add the sin and cos terms to get the magnitude
of the full particular solution

24. EFFECT OF SPEED ON THE
AMPLITUDE OF CAR VIBRATION

25. Thank You 