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Accelerating Random Vibration Tests

Test Generation

Vibration test facilities want to accurately test products in an efficient time period. There are a number of random vibration test options available for test engineers who want to break products quickly. Vibration Research has two techniques to help test engineers rapidly accelerate random vibration tests: kurtosis control and Fatigue Damage Spectrum.

Kurtosis Control (Kurtosion®)

Kurtosion logo and VibrationVIEW open on laptop

With Kurtosion, test engineers can accelerate test duration by adding the large and damaging resonant peaks from recorded data back into the random test. With traditional testing methods, the large resonant peaks are be averaged out by the controller.

The test engineer does not add any new energy to the system by adding these large resonant peaks. The PSD plot remains the same at all frequencies when the kurtosis level is increased. Rather, the distribution of energy changes so there is a greater occurrence of the large resonant peaks that are likely to fatigue the product faster. With Kurtosion®, test engineers can bring products to failure quickly without increasing the total energy of the test.

Fatigue Damage Spectrum (FDS)

With the Fatigue Damage Spectrum (FDS), test engineers accelerate the test duration by increasing the energy of the system.

Test engineers can increase the RMS of a test to fatigue a product faster. But to what level should they crank up the RMS? The answer depends on how long of a test the engineer wants to run (within reason).

With FDS, the test engineer uses the principle of Miner’s rule of damage. Fatigue damage will accumulate for a product until its life-dose of fatigue has been met. At that point, the product will experience some failure. Knowing this, test engineers can be confident that the total amount of fatigue for the product will not increase no matter the RMS level.

The VibrationVIEW software can compute the FDS from a recorded waveform. Based on the FDS, test engineers can set the test duration, and the software will compute a corresponding RMS value. With this method, the exact RMS (energy for the test) can be computed to bring about the failure of the product in the desired length of test time.

Conclusion

With the VibrationVIEW software, test engineers can choose how they want to accomplish an accelerated random vibration test.

  • Kurtosion: accelerate by keeping the RMS values the same but redistributing the energy to add more high-energy peaks.
  • FDS: Accelerate the test by increasing the RMS values.
Date

February 6, 2018

Author

Jared Van Baren

Category

Test Generation

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