Vibration Testing Ask the Expert

Electrodynamic vs Hydraulic Shakers: Which is best for your product?

Vibration testing is useful in designing high-quality, cost-effective products and shipping containers by accurately measuring sensitivity to sine or random vibrations. This testing is beneficial during product design, regulatory qualification, and production, helping to determine what degree items can physically and functionally withstand forces encountered in handling, transportation and service environments.

Two different types of shakers – electrodynamic shakers and hydraulic shakers – are commonly used to perform vibration testing. What is the difference between the two? Which type of shaker is best for your product?

An electrodynamic shaker uses technology that is analogous to a woofer speaker on a stereo system. The shaker uses a frequency generator to send a signal to a powerful current amplifier. This creates an electromagnetic force driving the armature of the shaker up and down the field coil located in the body of the shaker which is a large polarized electric magnet.

The hydraulic shaker uses a powerful hydraulic pump to create pressures of 2200 psi with flow rates of 55 gallons per minute to move the shaker head up and down. A proportional valve controls the vertical movement, driving the piston downward using negative control voltage and upwards using positive control voltage. The frequency generator of the vibration controller is outputting this voltage.

The two types of shakers are complementary technologies. The hydraulic shaker cannot respond as fast to control frequency but has a larger displacement (6 inches of head movement peak to peak). On the other hand, the electrodynamic vibration table can quickly respond to control frequency but its displacement is limited to the flux concentration of the field magnet (1-1.5 inches peak to peak).

The best way to differentiate the two types of shakers is to consider the types of vibrations they are simulating, as the different shakers have unique frequency ranges. A hydraulic shaker mimics the transportation vibrations found on a cargo ship rocked by waves in the ocean, a car going over a bridge, or a semi-trailer that hits a curb in the parking lot. The electrodynamic shaker is capable of higher frequencies, and simulates vibrations similar to a large church bell ringing or the booster stage of a rocket firing.

To sum things up, the best shaker to use for vibration testing depends upon what type of vibration the product is going to be subjected to in real life or what compliance standard it is being tested to conform. Each product and test process is unique, and it is important to utilize the resources and expertise of reliability engineers to develop the right test strategy for your products.

To learn more about vibration testing and ARL’s full range of testing services, please click here to contact our staff today.

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Recognized as one of the top product reliability labs in the country with a unique balance of testing, consulting and on-site staffing services, Austin Reliability Labs (ARL) is a place where we recognize the hard work and passion that goes into the design and development of your product and want to find any problems in an effort to perfect it. We also understand a reputation is something that builds over time, so we focus on establishing long-term partnerships with each of our clients. With that in mind, we not only specialize in writing and developing all of the tests that we perform, but, unlike other labs, we provide pass / fail reports on all of our tests and decipher the results for you in order to maximize your product’s success. In addition to our on-site staffing and consulting services, ARL’s full array of reliability testing services include: HALT / HASS, Battery Life Tests, Qualification Tests, Environmental Tests, Mechanical Tests, Additive Manufacturing Tests and Custom Tests.

We believe quality is infused by finding every flaw in a product and methodically removing each one until the product shines. As a result, only a thorough, comprehensive reliability test program, as provided by ARL, will allow a product to emerge that will earn or maintain an unsullied and clean brand reputation.