The adjustable mass damper

A tuned mass damper is a well-known concept that can be used to reduce undesired oscillation of structures. However, structures where the dynamic properties are difficult to estimate traditional mass damper need to be designed very carefully to make it work properly. For these kinds of structures an adjustable mass damper (AMD) is an effective vibration control tool. In this project a simple concept for the AMD was studied based on a leaf spring and moving mass. The moving mass was located in the middle of leaf spring and span length was adjusted using half cylinder shape supports. Aim of the concept was to make a simple low cost solution with wide control range. The frequency range of studied AMD was approximately from 20 to over 100 Hz. The AMD can be used as a troubleshooting device with structures that have resonance problem without extinctive pre study of the structure. Moving mass and span length can be varied easily so the adjusting of the AMD can be done in situ. The AMD was constructed using many thin plates that were piled like a leaf spring. All the parts in AMD are steel so the temperature range is wide and also the reliability is good. The AMD concept proved to work excellent in real scale laboratory test setup. Response of the self-excited 250 kg test table was decreased approximately 70 - 80 %. The studied AMD concept was designed to use in generator part of a diesel generator set. The AMD can also be used for example in other engine, manufacturing and transport applications.