Vibration Testing Services


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.

In qualifying new electronic and mechanical systems through the HALT/HASS process, the products undergo testing by applying both thermal and random vibration to identify weaknesses in the design before they are finalized for commercial production. “Random” vibration in a HALT chamber covers a broad band, between 5-5000Hz and can also obtain measurements up to 10,000 Hz. The HALT process does NOT focus its energy in the low frequency range (1-800Hz).

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.

sine sweep graph

Figure 1: Sine-Sweep 25-2000 Hz, 10G Two product accelerometers measured (purple, blue)


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.

Random Vibration Profile

Figure 2: Random Vibration 10-2000 Hz with breakpoints at 30Hz and 500Hz, Grms=13g

DynaQual can provide a “Transmissibility” plot for either mode of operation. This plot is simply 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. In Figure 3, the purple and blue curves represent two different accelerometer locations on a tested product. The transmissibility at seven different frequencies was measured. Note the highest ratio of 7.44 at approximately 400Hz.

Transmissibility

Figure 3: Transmissibility of above random profile highlighting possible resonance frequencies

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

Let us know if you don’t see the testing you need. DynaQual is planning to add complementary testing services such as Pressure, Calibration, X-ray, etc. We would like to hear from you regarding your interest obtaining these other testing services at our Houston location. Please use the inquiry form in the Contact Us tab to submit your request.