Vibration

DynaQual provides controlled vibration testing to cover the vibration frequency spectrum, from 5 Hz to 2,700 Hz, including low range frequencies not covered by HALT/HASS testing between 5 Hz and 800 Hz.

Shaker systems complement HALT/HASS testing but provide very different vibration profiles.These systems produce controlled inputs to the test article in various modes to excite the product in defined axes, over specific frequency spectrums and at set acceleration values.

The three common modes of operation on a Shaker system are as follows:

1. Sine-Sweep

The product under test is mechanically fixed to the table and a constant or variable amplitude (G’s) can be applied as the vibrating frequency of the shake system is increased at a set rate (Octaves per minute). The test specification can define the frequency range for the sweep, and the G amplitude. Application: Identifying resonance spikes in the product at specific frequencies.

Figure 1: Sine-Sweep 10-500 Hz, 1G three product accelerometers monitored

DynaQual also provides “Transmissibility” plots for either mode of operation, and demonstrated above in the lower plots. Simply put, it’s the ratio of the “g” amplitude of the control accelerometer (i.e.-affixed to the vibration plate) vs. the “g” amplitude of the accelerometer affixed to the product at strategic locations. This basic ratio represents the product Transmissibility and identifies potential resonances within the product that may need to be removed through redesign.

2. Random Vibration

The PUT is mechanically fixed to the table and random frequencies are applied. The customer can identify and request limits for ramp rates, maximum amplitude, break points in frequency and the overall Grms that the PUT is subjected to. These parameters determine the Power Spectral Density (PSD) for the test. Application:: Test product for ruggedness and durability, determine transmissibility. A steady application of random vibration will stress the product to its limits.

Figure 2: Random Vibration 20-2000 Hz

See the Shake Table specifications in the “Our Equipment” section.