Introduction to Vibration
Vibration testing is a subject which on first inspection may seem simple and straightforward. However, you will find that the subject is vast; requiring many skills and experience.
This page hopes to provide you with a general understanding of the subject and give you an awareness of some of the pitfalls you may encounter.
To perform a vibration test you require three main items:
- The vibration test system
- The vibration test specification
- The item to be tested
1) The vibration test system
As with any test equipment, the vibration test system with which you are provided has operational limitations; for example, a maximum rated travel. This is only one of many limitations that must be considered before performing any test. If the operational limitations of the vibration system are exceeded, a shorter system life can be expected. In simple terms, it's just like a car, the harder you drive it the more maintenance it will require. It is therefore essential that you know and understand the limitations of your system.
2) The vibration test specification
There are probably thousands of vibration test specifications. However, the question should always be asked: Is this the correct test for the product and will it test the product satisfactorily? All tests should be questioned, as there is a high probability that it may over-test or under-test the product in question.
3) The item to be tested
The test item must be fixed to the vibration table. This is done using a fixture (jig). The fixture must transfer the vibration from the table to the test item without adversely influencing the test. Although this may seem simple, it is not. Time and consideration must be given to the fixture design.
The vibration that is transferred to the test item must be measured and controlled. The measurement is usually done using one or more accelerometers, but where and how the accelerometers are placed is critical and must form part of a control strategy.