Tuned Mass Damper In Contrast To Viscous Damper

There are numerous damper solutions for dampening undesirable vibration. A magnetorheological attenuator and a tuned mass damper (TMD), for example. Here we focus on the benefits and negative aspects of those two actuators.

TMD Pros and Cons

The concept of a tuned mass damper is to somehow intelligently act in response to shake. A distinction I follow is that a tuned mass damper creates a counteracting force by moving about a mass at reverse cycle with the source vibration.

A benefit of a TMD is evidently its capability to make a significant change by imposing a force to the shaking process because of a moving mass. This can also be one of its major problems. If you ever apply the force systematically at a wrong instant, the vibration system may become instable in case the motion of the TMD happens in the resonance wavelength. And functioning at the resonance frequency is somewhat common, as the resonance pitch is many times the one being killed. Ok, it is true that with a semi-active actuator there’s also the danger of screwing up with something at the resonance frequency by handling the actuator poorly, but at least no additional force with a moving mass is used and due to this fact the future damage is not as damaging.

An extra negative aspect is the increased selection of moving items. A tuned mass damper is additionally the one which necessitates the most hand-operated assembly labor.

Semi-Active Damper Benefits and Drawbacks

The operating principle of a semi-active damper is based on the material aspects. When it comes to magnetorheological actuator, the dampening substance varies its viscosity. The content is a ferrofluid: oil containing metallic particles. The theory is that when you put on a magnetic field to the matter, the metallic particles are arranged according to the field lines and get the fluid stiff. This produces in practice a damper that may be turned on and off in just milliseconds.

A disadvantage of the damper is obviously its somewhat reduced quantity of usage. This is mostly because of the fact that it’s rather fresh alternative on the market and not very widely tested yet. On the other hand, this is constantly changing since the systematic research material builds up.

In my view, the semi-active actuator combines the greatest components of the previous actuator categories:

  • Small dimension
  • A small amount of moving items
  • Responds real-time to a selection of vibration frequencies

Moreover, as a result of its little size the magnetorheological actuator may be attached beside a present passive attenuator that is already attenuating certain frequencies. The magnetorheological actuator can then focus on the vibration that can vary with time.