11/22/2022

Choosing a simple Anti-Vibration Mount? Part 1: Basic Principles

 Written by Daniel Lawes

Note: This description is intentionally simplified to help educate and inform.  If of sufficient interest, we will produce more material which goes into more detail.

The key here, is really very simple; if something wants to vibrate then, often, we should let it.  Vibration is generally where something tries to move or bounce one way, then bounce back again – it generally wants to return to the same position (approximately).

To say the same thing a little more technically; imagine a sine wave, this represents the vibratory forces moving one way then the other.  The wave keeps coming back to the X-axis, or start point – it wants to return to the same place, but continuously ‘dance’ one way then the other.

Trying to stop this movement completely, and hold the ‘wave’ in place on the x-axis, is hard work and results in all of the energy produced by ‘the dance’ being transmitted through to the floor (or other structure e.g. chassis).  The dance is still trying to happen despite being constrained.  The more you can allow it to do its ‘thing’ without letting it run away, the less energy is transmitted.

So, let’s say we allow 60-70% of the movement in each direction to occur, then the vibration related energy transmitted through to the surroundings is reduced by considerably more than the 60-70%.

So, how to we hold something securely but allow it to move just enough?  Use a flexible connection – rather than bolting something firmly together, use a rubber (or other flexible material e.g. spring) product designed for the job.

Below is an example of a simple ‘rubber bobbin’ in different configurations.  The metal fixtures are held together by the rubber, they are not directly connected, as can be seen in the third image with translucent rubber.  They are flexibly connected and therefore ‘de-coupled’:

Why doesn’t a car engine vibrate the occupants to pieces?  Why doesn’t a washing machine vibrate the whole building?  The answer relate to flexible connections which de-couple the vibrating part from its surroundings.

Relevant Links:

For other parts of of this lesson, click here:

1. Introduction to this lesson
2. Static Deflection
3. Load
4. Mount Selection