| dc.description.abstract | Vibration control is very important in many areas including machine operation and
daily life. Semi-active vibration control integrates a tuning control scheme with a tunable
vibration absorber for suppression of vibration due to a harmonic excitation with a
variable excitation frequency.
The electromagnetic vibration absorber (EMVA) is a semi-active vibration device
whose stiffness can be tuned on-line. In this study, the EM VA is used for non-collocated
vibration control. The study consists of two parts. In the first part, the characterization of
the EMVA is revisited using a commercial FE package, Comsol Multiphysics. Various
single physics models are built including the electromagnetic coil, the electromagnetic
coil with a core, and a permanent magnet (PM) placed between a pair of PMs. These
models are used to study the magnetic density in the gap of the electromagnet. A
coupling model that involves magnetism and structural mechanics is built. This model is
used to study the factors that affect the magnetic stiffness.
In the second part, the EMVA is implemented to suppress vibration of a structure that
can be modeled as a three-degree-of-freedom system. The non-collocated control theory
is reviewed. The EM VA is modified to allow both manual adjustment and on-line tuning.
Three different control methods, FFT-based method, FFT-based plus fine tuning method,
and RM S-based method, are developed. The experimental results using the three methods
are compared. | |
