Vibration testing is essential to determining the ability of a product to withstand the conditions it might experience during its lifetime. The testing simulates conditions that occur in operations and transit and stretches across many industries. This testing assists in finding potential issues before they arise.
Without shaker testing, car seats would squeak with every change in the road surface. Airplanes would require significant repair after every flight. Consumer electronics would have shorter lifespans. Vibration testing is essential to maximizing the use and life of nearly every product.
Random Vibration Testing
A random vibration test provides all frequencies simultaneously. This is considered to simulate real-world movement and is the more realistic of the two primary types of vibrations. Random vibration tests can simulate vibration caused by different events such as operation, transportation and seismic.
Products can have multiple resonant frequencies. Random testing applies multiple frequencies at the same time. This process can expedite the analysis of the product providing valuable product life information in a short period of time. This saves significant time and money by reducing the need for repairs, maintenance and recalls.
Sine Vibration Testing
This test sweeps across a frequency spectrum. This determines and identifies any test article resonant frequencies. Sine sweeps are also called sinusoidal sweeps. Sine sweeps can identify the frequencies that generate the largest responses.
During product validation, a sine test can be used to maintain the shaker on the product’s resonance frequency. This is referred to as a Sine Dwell Vibration Test. This will essentially fatigue the product and either expedite a failure or show proof of the product’s ability to survive.
As a regulatory compliance test lab, we use sine sweeps to validate our shakers and fixtures. Shakers can develop issues such as cracked armatures and loose connections. Fixtures can have resonance frequencies as well. A fixture should never have a resonance in the frequency range of the test plan.
Mixed-Mode Vibration Testing
In addition to Random and Sine, there are also combination vibration profiles that can be used. These are called Mixed-Mode Vibration Tests.
One example of a mixed-mode test is Sine on Random Vibration Testing. These tests provide further insight on the ability of a product to survive. The testing combines the underlying energy of a random vibration test with the resonance dwells of the sine test. The sine component of these mixed-mode tests can either be sweeping or fixed for the device under test.
An excellent example of a mixed-mode event is a helicopter. The helicopter incurs random vibration during flight. Add a missile launch or gunfire to it and an intense sinusoidal vibration is introduced. This combination of vibration events can impact operations of the aircraft and its components.
Mixed-mode testing such as sinusoidal on random is not required for all products. Specific testing requirements are often determined by a product’s industry. For More info....
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