When Should I Use RANDOM Vibration Testing?

Vibration Control

When preparing to run a vibration test, a test engineer is faced with the question of what kind of test should be run with any particular set-up.  One option is a RANDOM vibration test.

What is RANDOM

A RANDOM vibration test is a test that simultaneously sends random vibrations that over time include the entire vibration test’s frequency range. For example, consider Figure 1, in which a test profile is displayed that tests an item from 50 Hz to 4000 Hz.  In Figure 2, the acceleration waveform for that test is displayed. The display shows a “ragged” plot, in which random amplitude vibrations are being used to test the DUT (Device Under Test).

Figure 1:  A RANDOM test profile from 50 to 4000 Hz.

Figure 2: The acceleration waveform for a RANDOM vibration test. Note the random amplitudes of the accelerations experienced by the DUT.


Why Should I Use RANDOM?

Random vibration testing is beneficial for several reasons:

  1. The “real-world” is less synthetic than a single sine wave. Exciting all the frequencies makes a random test a more realistic representation of what occurs in the “real-world”.
  2. A random test can be created to represent multiple environments under which the DUT may be used in the “real-world”
  3. A random test can be accelerated to create a test representative of a longer field life than may be practically run in a lab.
  4. A DUT may have multiple resonances. Sine testing can only test one resonance at a time and cannot test the interactions of multiple resonances.  By exciting all resonances at the same time, random vibration gets a glimpse of the interaction between these multiple resonances.

When Should I Use RANDOM?

Vibration test engineers should use random vibration testing when:

  • Looking to test a product for “real-life” vibrations.
  • Looking to see how a product will respond to multiple resonances being excited at the same time.

Testing a product to failure.  Bringing the product to failure using a sine-track-and-dwell at one frequency ignores how vibrations at other frequencies affect the failure rate.  Random vibration testing will result in a faster failure mode since all frequencies in the test profile are tested simultaneously.

Download VR’s Random Test Guide by filling out the form below:

As the innovator in vibration control, Vibration Research wants to help your company run more efficient and effective vibration tests.


Sep 19, 2016 11:45:18 AM


Jordan Van Baren


Vibration Control

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