technical seminar-vibration isolators

8/7/2019 TECHNICAL SEMINAR-VIBRATION ISOLATORS

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VIBRATION ISOLATORS

ByS. Vivek

07671A03A8


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Vibration is the oscillation of a rigid or elastic body that is created by the

transfer of energy from one body to another.

Transportation vehicles, portable devices and consumer electronics all

contain parts that are constantly in motion and subject to vibration.

The movement of these parts creates energy that radiates audible noise in

the form of vibration.

Vibration can damage sensitive equipment and reduce the reliability of an

otherwise durable product.

To avoid the possibility of damage and ensure proper performance for

the long term, sensitive components should be isolated from vibration

energy.


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Methods of Vibration Control

Avoid Resonance

Balancing /Control of Excitation Forces

Adequate Damping

Vibration Isolation

Vibration Absorber


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The transmission of vibratory motions or

forces from one structure to another may

be reduced by interposing a relatively

flexible isolating element between the two

structures. This is called vibration

isolation

Such systems are used extensively

to isolate machinery (industrial

and marine), civil engineeringstructures (base isolation in

building, bridges, etc.), and sensitive

components from the foundation/base.


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It is important to distinguish

between vibration dampingand

vibration isolation.

The dampingof a structural

mode consists in reducing the

response of the structure near the

corresponding natural frequency.

Isolation, on the other hand, consists in reducing the vibrationtransmission from one part of the structure (sometimes called noisy

side) to the other(quiet side): the reduction of the transmission

generally occurs in a large frequency region.


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Isolating the structures from the

vibrations is very important due to

1. To protect sensitive items, such as delicate electronic components,

from high environmental vibration levels.

2. To reduce the magnitude of the oscillatory forces transmitted to the

supports, when inertial or other forces are developed in a machine.

3. Sound generated due to vibrations

is to be in limits

4. Vibration of the buildings due to the

equipment present in them.


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Isolators act as springs that

deflect energy as vibrations

impact their surface and then

rebound to return the vibration

energy back towards the source.

Reducing structure-borne excitation can extend the life of

transportation vehicles, portable devices and consumer electronics

and prevent performance problems.


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Oscillating Force Fd is

internal to massM

Isolator has stiffness

K=Weight/Static Deflection()

Goal is to minimize the

transmitted force into the

building, Ft

Natural or Resonate Frequency of the oscillation


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SOURCE-PATH-RECEIVERMODEL


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Source: a mechanical or fluid disturbance, generated internally by the machine,such as unbalance, torque pulsations, gear tooth meshing, fan blade passing, etc.

These typical occur at frequencies which are integer multiples of the rotating

frequency of the machine.

P

ath: the structural or airborne path by which the disturbance is transmitted tothe receiver.

Receiver: the responding system, generally having many natural frequencies

which can potentially be excited by vibration frequencies generated by the

source. (M

urphy says the natural frequency of the system will always coincidewith an excitation frequency.


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Solutions in Source-path-recivermodel:

1. Relocate machine

2. Replace machine3. Change the operating speed

4. Balance rotating elements

5. Using isolator springs and/or inertia blocks

6. Change the natural frequencies of the system

7. Add structural damping


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1. Many isolation systems involve

center-of-gravity installations of

the equipment. That is, the

center-of-gravityof the equipment

coincides with the elastic center

of the isolation system.

2. Many equipment isolation systems

are required to be isoelastic. That is, the system

translational spring rates in all directions are the same.

3. Many pieces of equipment are relatively light in weight and Support structures are

relatively rigid incomparison to the stiffness of the isolators used to support and

protect the equipment.


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THANK YOU

technical seminar-vibration isolators

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