Shake It Up!

Shake It Up!

15th May 2015


An electrodynamic shaker, now at ESI

How does it work?

An electrodynamic shaker is used to help solve real world problems involving vibration of floors and footbridges. They use electrical current and magnets to oscillate a heavy piston up and down at a specific frequency, or range of frequencies, as controlled by an amplifier. Different amounts of weight can be placed on the top of the shaker to help drive the floor response. It doesn't take much to get the floor moving a small amount. Watch the video!


During shaking, a sensitive accelerometer is placed on the floor and a data collector measures the response at different frequencies. It is that simple. Learn more about this technology at APS Dynamics.

How can this technology help you?

Demands on buildings housing sensitive medical diagnostic and research equipment like MRIs, CTs, SEMs and nano-manufacturing equipment are increasing. Often this equipment needs to be located in existing buildings seldom constructed for these specialized uses.


Determining the modifications necessary to achieve low vibration levels on existing floors requires knowledge of the modal characteristics of the structure. What does this mean? Basically, modes are the frequencies at which the floor naturally tends to vibrate - much like a string on a guitar. The picture below of a computer model of a floor from a real hospital project helps illustrate the shape of a vibration mode.



When the floor's natural frequencies are known, it allows the engineer to assess expected vibration of the floor against manufacturer criteria, recommend improvements to optimize performance, and to investigate other vibration control techniques like tuned-mass dampers (TMDs). Ultimately, the more that is known about the floor the better the design will be, and good design brings less risk for the owner.

Who can perform these measurements?

A vibration expert who has the latest in measurement technology and the knowledge to interpret the results is crucial. ESI Engineering has both the equipment and expertise necessary to provide a solution for the vibration aspect of your project.  Visit our website for more information.